> [!abstract] Summary > **Reference dictionary of commonly used HScript expressions** in Houdini. Every entry links to the official SideFX documentation. Use as a lookup — search the page (`Ctrl+F`) for the expression you need. > [!info] Source > Full official list: [SideFX — Houdini Expressions](https://www.sidefx.com/docs/houdini/expressions/index.html). --- ### Commonly Used Expressions You can find the full list of Houdini expressions here: [https://www.sidefx.com/docs/houdini/expressions/index.html](https://www.sidefx.com/docs/houdini/expressions/index.html) - [abs](https://www.sidefx.com/docs/houdini/expressions/abs.html) Returns the absolute value of the argument. - [abspath](https://www.sidefx.com/docs/houdini/expressions/abspath.html) Returns the full path of a file. - [acos](https://www.sidefx.com/docs/houdini/expressions/acos.html) Returns the arc-cosine of the argument. - [angvel](https://www.sidefx.com/docs/houdini/expressions/angvel.html) Returns the angular velocity required to rotate an object from one orientation to another in a certain period of time. - [arclen](https://www.sidefx.com/docs/houdini/expressions/arclen.html) Returns the arc length of a curve between two U positions. - [arclenD](https://www.sidefx.com/docs/houdini/expressions/arclenD.html) Returns the arc length of a curve between two U positions and number of divisions. - [arg](https://www.sidefx.com/docs/houdini/expressions/arg.html) Returns an argument from a list of HScript-style arguments. - [argc](https://www.sidefx.com/docs/houdini/expressions/argc.html) Returns the number of arguments in an HScript-style list of arguments. - [asin](https://www.sidefx.com/docs/houdini/expressions/asin.html) Returns the arc-sine of the argument. - [atan](https://www.sidefx.com/docs/houdini/expressions/atan.html) Returns the arc-tangent of the argument. - [atan2](https://www.sidefx.com/docs/houdini/expressions/atan2.html) Returns the arc-tangent of y/x. - [atof](https://www.sidefx.com/docs/houdini/expressions/atof.html) Converts a string to a float. - [attriblist](https://www.sidefx.com/docs/houdini/expressions/attriblist.html) Returns a space-separated list of attribute names. - [bbox](https://www.sidefx.com/docs/houdini/expressions/bbox.html) Returns bounding box information for a surface node. - [bezier](https://www.sidefx.com/docs/houdini/expressions/bezier.html) Channel segment function: Bezier interpoloation spline - [bitand](https://www.sidefx.com/docs/houdini/expressions/bitand.html) Combines two numbers with bitwise-and. - [bitor](https://www.sidefx.com/docs/houdini/expressions/bitor.html) Combines two numbers with bitwise-or. - [bitset](https://www.sidefx.com/docs/houdini/expressions/bitset.html) Sets or clears a bit in a number. - [bittest](https://www.sidefx.com/docs/houdini/expressions/bittest.html) Returns if a given bit is set. - [bitxor](https://www.sidefx.com/docs/houdini/expressions/bitxor.html) Combines two numbers with bitwise-xor. - [boneangle](https://www.sidefx.com/docs/houdini/expressions/boneangle.html) Returns the angle at the joint between two bone objects. - [ceil](https://www.sidefx.com/docs/houdini/expressions/ceil.html) Returns the smallest integer not less than the value passed in. - [centroid](https://www.sidefx.com/docs/houdini/expressions/centroid.html) Returns centroid information for a surface node. - [ch](https://www.sidefx.com/docs/houdini/expressions/ch.html) Returns the value of a parameter. - [chexist](https://www.sidefx.com/docs/houdini/expressions/chexist.html) Returns 1 if the specified channel exists, 0 if it doesn’t. - [chexpr](https://www.sidefx.com/docs/houdini/expressions/chexpr.html) Evaluates a channel with a new segment expression. - [chexprf](https://www.sidefx.com/docs/houdini/expressions/chexprf.html) Evaluates a channel with a new segment expression at a given frame. - [chexprt](https://www.sidefx.com/docs/houdini/expressions/chexprt.html) Evaluates a channel with a new segment expression at a given time. - [chf](https://www.sidefx.com/docs/houdini/expressions/chf.html) Evaluates a parameter at a given frame. - [chgroup](https://www.sidefx.com/docs/houdini/expressions/chgroup.html) return a string containing all of the channels contained in a group. - [chop](https://www.sidefx.com/docs/houdini/expressions/chop.html) Evaluates a channel within a CHOP at the current time. - [chopcf](https://www.sidefx.com/docs/houdini/expressions/chopcf.html) Evaluates a channel within a CHOP at a given time. - [chopci](https://www.sidefx.com/docs/houdini/expressions/chopci.html) Evaluates a channel within a CHOP at a specified sample point. - [chopct](https://www.sidefx.com/docs/houdini/expressions/chopct.html) Evaluates a channel within a CHOP at a specified time. - [chope](https://www.sidefx.com/docs/houdini/expressions/chope.html) Returns the end index of the channels in a CHOP. - [chopf](https://www.sidefx.com/docs/houdini/expressions/chopf.html) Evaluates a channel within a CHOP with at a given frame. - [chopi](https://www.sidefx.com/docs/houdini/expressions/chopi.html) Evaluates a channel within a CHOP at a given sample point. - [chopl](https://www.sidefx.com/docs/houdini/expressions/chopl.html) Returns the length of the channels in a CHOP, in samples. - [chopn](https://www.sidefx.com/docs/houdini/expressions/chopn.html) Returns the number of data channels within a CHOP. - [chopnames](https://www.sidefx.com/docs/houdini/expressions/chopnames.html) Returns the names of all the data channels within a CHOP. - [chopr](https://www.sidefx.com/docs/houdini/expressions/chopr.html) Returns the sample rate of a CHOP. - [chops](https://www.sidefx.com/docs/houdini/expressions/chops.html) Returns the start index of a CHOP. - [chopstr](https://www.sidefx.com/docs/houdini/expressions/chopstr.html) Returns the string value of a channel within a CHOP at the current time. - [chopt](https://www.sidefx.com/docs/houdini/expressions/chopt.html) Returns the value of a channel within a CHOP at a specified time. - [chramp](https://www.sidefx.com/docs/houdini/expressions/chramp.html) Returns the value of a ramp parameter at a specific position. - [chrampf](https://www.sidefx.com/docs/houdini/expressions/chrampf.html) Returns the value of a ramp parameter at a specific position and frame. - [chrampt](https://www.sidefx.com/docs/houdini/expressions/chrampt.html) Returns the value of a ramp parameter at a specific position and time. - [chs](https://www.sidefx.com/docs/houdini/expressions/chs.html) Evaluates the string value of a parameter at the current time. - [chsop](https://www.sidefx.com/docs/houdini/expressions/chsop.html) Evaluates the parameter at the current time as a node path string. - [chsoplist](https://www.sidefx.com/docs/houdini/expressions/chsoplist.html) Evaluates the parameter at the current time as a node path list string. - [chsraw](https://www.sidefx.com/docs/houdini/expressions/chsraw.html) Returns the raw (unexpanded) expression value of a parameter as a string. - [cht](https://www.sidefx.com/docs/houdini/expressions/cht.html) Returns the value of a parameter at a specified time. - [clamp](https://www.sidefx.com/docs/houdini/expressions/clamp.html) Returns a value clamped between a minimum and maximum. - [clamptosphere](https://www.sidefx.com/docs/houdini/expressions/clamptosphere.html) Clamps a vector to always end between a minimum and maximum sphere. - [constant](https://www.sidefx.com/docs/houdini/expressions/constant.html) Channel segment function: constant value. - [contextoption](https://www.sidefx.com/docs/houdini/expressions/contextoption.html) Returns the value of context option as a floating point value. - [contextoptions](https://www.sidefx.com/docs/houdini/expressions/contextoptions.html) Returns a cook context option as a string value. - [cophasmeta](https://www.sidefx.com/docs/houdini/expressions/cophasmeta.html) Tests if metadata exists on a compositing node. - [cophasplane](https://www.sidefx.com/docs/houdini/expressions/cophasplane.html) Tests if a plane exists on a compositing node. - [copmeta](https://www.sidefx.com/docs/houdini/expressions/copmeta.html) Returns numeric metadata from a compositing node. - [copmeta](https://www.sidefx.com/docs/houdini/expressions/copmetas.html) Returns string metadata from a compositing node. - [cos](https://www.sidefx.com/docs/houdini/expressions/cos.html) Returns the cosine of the argument. - [cosh](https://www.sidefx.com/docs/houdini/expressions/cosh.html) Returns the hyperbolic cosine of the argument. - [cross](https://www.sidefx.com/docs/houdini/expressions/cross.html) Computes the cross-product of two vectors. - [cubic](https://www.sidefx.com/docs/houdini/expressions/cubic.html) Channel segment function: cubic spline. - [cucwc](https://www.sidefx.com/docs/houdini/expressions/cucwc.html) Deprecated: current working container for custom panels. - [cudatatype](https://www.sidefx.com/docs/houdini/expressions/cudatatype.html) Deprecated: data type of a gadget, for custom panels. - [cumenuadd](https://www.sidefx.com/docs/houdini/expressions/cumenuadd.html) Deprecated: adds a menu entry on a custom panel. - [cuquery](https://www.sidefx.com/docs/houdini/expressions/cuquery.html) Deprecated: returns a value from a custom panel. - [curvature](https://www.sidefx.com/docs/houdini/expressions/curvature.html) Returns the curvature of the surface at the given UV coordinates. - [cutype](https://www.sidefx.com/docs/houdini/expressions/cutype.html) Deprecated: Returns the type of a gadget on a custom panel. - [cycle](https://www.sidefx.com/docs/houdini/expressions/cycle.html) Channel segment function: repeats animation from previous frames. - [cycleoffset](https://www.sidefx.com/docs/houdini/expressions/cycleoffset.html) Channel segment function: repeats the animation between frames f1 and f2, accumulating the value. - [cycleoffsett](https://www.sidefx.com/docs/houdini/expressions/cycleoffsett.html) Channel segment function: repeats the animation between times t1 and t2, accumulating the value. - [cyclet](https://www.sidefx.com/docs/houdini/expressions/cyclet.html) Channel segment function: repeats animation from previous frames. - [decode](https://www.sidefx.com/docs/houdini/expressions/decode.html) Decodes a variable name that was previously encoded. - [decodeattrib](https://www.sidefx.com/docs/houdini/expressions/decodeattrib.html) Decodes a geometry attribute name that was previously encoded. - [decodeparm](https://www.sidefx.com/docs/houdini/expressions/decodeparm.html) Decodes a node parameter name that was previously encoded. - [deg](https://www.sidefx.com/docs/houdini/expressions/deg.html) Converts from radians to degrees. - [degree](https://www.sidefx.com/docs/houdini/expressions/degree.html) Returns the degree a specified face or hull. - [detail](https://www.sidefx.com/docs/houdini/expressions/detail.html) Returns the value of a detail attribute. - [detailattriblist](https://www.sidefx.com/docs/houdini/expressions/detailattriblist.html) Returns a space-separated list of detail attribute names. - [detailattribsize](https://www.sidefx.com/docs/houdini/expressions/detailattribsize.html) Returns the number of components in a detail attribute. - [detailattribtype](https://www.sidefx.com/docs/houdini/expressions/detailattribtype.html) Returns the type of a detail attribute. - [details](https://www.sidefx.com/docs/houdini/expressions/details.html) Returns the string value of a detail attribute. - [detailsmap](https://www.sidefx.com/docs/houdini/expressions/detailsmap.html) Returns a string from a list of strings in a detail attribute. - [detailsnummap](https://www.sidefx.com/docs/houdini/expressions/detailsnummap.html) Returns the number of unique strings bound to a detail attribute. - [detailvals](https://www.sidefx.com/docs/houdini/expressions/detailvals.html) Returns components of a string array attribute. - [determinant](https://www.sidefx.com/docs/houdini/expressions/determinant.html) Returns the determinant of a matrix. - [dihedral](https://www.sidefx.com/docs/houdini/expressions/dihedral.html) Computes the dihedral matrix between vectors v0 and v1. - [distance](https://www.sidefx.com/docs/houdini/expressions/distance.html) Returns the distance between two 3D points. - [dopallfields](https://www.sidefx.com/docs/houdini/expressions/dopallfields.html) Returns a space separated list of all the field names that can be passed to the dopfield function. - [dopcontextgeo](https://www.sidefx.com/docs/houdini/expressions/dopcontextgeo.html) Returns the full path of the node connected to a dopnetwork. - [dopcountslices](https://www.sidefx.com/docs/houdini/expressions/dopcountslices.html) Returns the number of records of a given type in a piece of dynamics data. - [dopfield](https://www.sidefx.com/docs/houdini/expressions/dopfield.html) Returns the value of a field as a float. - [dopfieldname](https://www.sidefx.com/docs/houdini/expressions/dopfieldname.html) Returns the name of a DOP field. - [dopfields](https://www.sidefx.com/docs/houdini/expressions/dopfields.html) Returns the value of a DOP field as a string. - [dopfieldtype](https://www.sidefx.com/docs/houdini/expressions/dopfieldtype.html) Returns the type of a DOP field. - [dopframe](https://www.sidefx.com/docs/houdini/expressions/dopframe.html) Returns the current frame of the simulation. - [dopframetost](https://www.sidefx.com/docs/houdini/expressions/dopframetost.html) Returns the simulation time equivalent of a simulation frame. - [dopgrouphasobject](https://www.sidefx.com/docs/houdini/expressions/dopgrouphasobject.html) Returns 1 if a specified DOP group contains a specified object. - [dopgroupismutual](https://www.sidefx.com/docs/houdini/expressions/dopgroupismutual.html) Returns 1 if a specified DOP group is mutually affecting. - [dopgrouplist](https://www.sidefx.com/docs/houdini/expressions/dopgrouplist.html) returns a string containing a list of all object groups for the current time in a specified DOP Network. - [dophasfield](https://www.sidefx.com/docs/houdini/expressions/dophasfield.html) Returns 1 if a specified DOP field exists. - [dophassubdata](https://www.sidefx.com/docs/houdini/expressions/dophassubdata.html) Returns 1 if a dynamics object has the specified subdata. - [dopnodeobjs](https://www.sidefx.com/docs/houdini/expressions/dopnodeobjs.html) Returns the list of objects processed by a DOP in the latest timestep. - [dopnumfields](https://www.sidefx.com/docs/houdini/expressions/dopnumfields.html) Returns the number of fields in a DOP record type. - [dopnumobjects](https://www.sidefx.com/docs/houdini/expressions/dopnumobjects.html) returns the number of objects in a simulation. - [dopnumrecords](https://www.sidefx.com/docs/houdini/expressions/dopnumrecords.html) Returns the number of records of a given type in a piece of dynamics data. - [dopnumrecordtypes](https://www.sidefx.com/docs/houdini/expressions/dopnumrecordtypes.html) Returns the number of types of record in a piece of dynamics data. - [dopnumsubdata](https://www.sidefx.com/docs/houdini/expressions/dopnumsubdata.html) Returns the number of subdata items attached to an object or data. - [dopobjectlist](https://www.sidefx.com/docs/houdini/expressions/dopobjectlist.html) Returns all objects matching the an object specification. - [dopobjectsareaffectors](https://www.sidefx.com/docs/houdini/expressions/dopobjectsareaffectors.html) Tests whether a set of objects has an affector relationship with another object. - [dopobjscreatedby](https://www.sidefx.com/docs/houdini/expressions/dopobjscreatedby.html) Returns the list of objects created by a particular DOP node. - [dopoption](https://www.sidefx.com/docs/houdini/expressions/dopoption.html) Returns the value of a DOP field as a float. - [dopoptions](https://www.sidefx.com/docs/houdini/expressions/dopoptions.html) Returns the value of a DOP field as a string. - [doprecordtypename](https://www.sidefx.com/docs/houdini/expressions/doprecordtypename.html) Returns the name of a record in DOPs data given its index. - [dopsolvedopnet](https://www.sidefx.com/docs/houdini/expressions/dopsolvedopnet.html) Script solver support function. - [dopsolvenewobject](https://www.sidefx.com/docs/houdini/expressions/dopsolvenewobject.html) Script solver support function. - [dopsolvenumnewobjects](https://www.sidefx.com/docs/houdini/expressions/dopsolvenumnewobjects.html) Script solver support function. - [dopsolvenumobjects](https://www.sidefx.com/docs/houdini/expressions/dopsolvenumobjects.html) Script solver support function. - [dopsolveobject](https://www.sidefx.com/docs/houdini/expressions/dopsolveobject.html) Script solver support function. - [dopsolvetimestep](https://www.sidefx.com/docs/houdini/expressions/dopsolvetimestep.html) Script solver support function. - [dopsttoframe](https://www.sidefx.com/docs/houdini/expressions/dopsttoframe.html) returns the simulation frame of a given simulation time. - [dopsttot](https://www.sidefx.com/docs/houdini/expressions/dopsttot.html) Returns the global time of a given simulation time. - [dopsubdataname](https://www.sidefx.com/docs/houdini/expressions/dopsubdataname.html) Returns the name of a subdata of a given DOP object. - [doptime](https://www.sidefx.com/docs/houdini/expressions/doptime.html) Returns the current time of a simulation. - [doptransform](https://www.sidefx.com/docs/houdini/expressions/doptransform.html) Returns a transformation matrix associated with a piece of data. - [dopttost](https://www.sidefx.com/docs/houdini/expressions/dopttost.html) Returns the simulation time equivalent to a given global time. - [dopvelatpos](https://www.sidefx.com/docs/houdini/expressions/dopvelatpos.html) Returns the velocity that a point at a location in simulation space would have if it were attached to a DOP object. - [dot](https://www.sidefx.com/docs/houdini/expressions/dot.html) Computes the dot product of two vectors. - [ease](https://www.sidefx.com/docs/houdini/expressions/ease.html) Channel segment function: ease-in and -out. - [easein](https://www.sidefx.com/docs/houdini/expressions/easein.html) Channel segment function: ease-in. - [easeinp](https://www.sidefx.com/docs/houdini/expressions/easeinp.html) Channel segment function: ease-in with configurable acceleration. - [easeout](https://www.sidefx.com/docs/houdini/expressions/easeout.html) Channel segment function: ease-out - [easeoutp](https://www.sidefx.com/docs/houdini/expressions/easeoutp.html) Channel segment function: ease-out with configurable acceleration. - [easep](https://www.sidefx.com/docs/houdini/expressions/easep.html) Channel segment function: ease-in and -out with configurable acceleration. - [edgegrouplist](https://www.sidefx.com/docs/houdini/expressions/edgegrouplist.html) Returns the list of edge groups in a surface node. - [edgegroupmask](https://www.sidefx.com/docs/houdini/expressions/edgegroupmask.html) Returns the list of edge groups matching a pattern in a surface node. - [efit](https://www.sidefx.com/docs/houdini/expressions/efit.html) Fits a value from one range to another. - [encode](https://www.sidefx.com/docs/houdini/expressions/encode.html) Encodes any string into a valid variable name. - [encodeattrib](https://www.sidefx.com/docs/houdini/expressions/encodeattrib.html) Encodes any string into a valid geometry attribute name. - [encodeparm](https://www.sidefx.com/docs/houdini/expressions/encodeparm.html) Encodes any string into a valid node parameter name. - [eval](https://www.sidefx.com/docs/houdini/expressions/eval.html) Evaulates a string as an expression returning a float. - [evals](https://www.sidefx.com/docs/houdini/expressions/evals.html) Evaulates a string as an expression returning a string. - [execute](https://www.sidefx.com/docs/houdini/expressions/execute.html) Runs a string as an HScript command and returns the command’s output. - [executeb](https://www.sidefx.com/docs/houdini/expressions/executeb.html) Runs a string as an HScript command and returns the command and error output. - [executee](https://www.sidefx.com/docs/houdini/expressions/executee.html) Runs a string as an HScript command and returns any error output. - [exp](https://www.sidefx.com/docs/houdini/expressions/exp.html) Returns the logarithmic exponentiation of the argument. - [explodematrix](https://www.sidefx.com/docs/houdini/expressions/explodematrix.html) Explodes a 3×3 or 4×4 matrix into the euler rotations required to rebuild it. - [explodematrixp](https://www.sidefx.com/docs/houdini/expressions/explodematrixp.html) Explodes a 3×3 or 4×4 matrix into the euler rotations required to rebuild it. - [explodematrixpr](https://www.sidefx.com/docs/houdini/expressions/explodematrixpr.html) Explodes a 3×3 or 4×4 matrix into the euler rotations required to rebuild it. - [findfile](https://www.sidefx.com/docs/houdini/expressions/findfile.html) Searches the Houdini path for a file. - [findfiles](https://www.sidefx.com/docs/houdini/expressions/findfiles.html) Searches the Houdini path for a file or directory. - [fit](https://www.sidefx.com/docs/houdini/expressions/fit.html) Fits a value from one range to another. - [fit01](https://www.sidefx.com/docs/houdini/expressions/fit01.html) Fits a value to the 0-1 range. - [fit10](https://www.sidefx.com/docs/houdini/expressions/fit10.html) Fits a number in the 0-1 range. - [fit11](https://www.sidefx.com/docs/houdini/expressions/fit11.html) Fits a number to the -1 to 1 range. - [floor](https://www.sidefx.com/docs/houdini/expressions/floor.html) Returns the largest integer not greater than a number. - [fpadzero](https://www.sidefx.com/docs/houdini/expressions/fpadzero.html) Returns a string padding a number to a given length with zeros. - [frac](https://www.sidefx.com/docs/houdini/expressions/frac.html) Returns the fractional part of a floating-point number. - [ftoa](https://www.sidefx.com/docs/houdini/expressions/ftoa.html) Converts a number to a string. - [ftrim](https://www.sidefx.com/docs/houdini/expressions/ftrim.html) Converts a number to a string, with rounding. - [groupbyval](https://www.sidefx.com/docs/houdini/expressions/groupbyval.html) Returns a string describing the set of elements with a given value for an integer attribute. - [groupbyvals](https://www.sidefx.com/docs/houdini/expressions/groupbyvals.html) Returns a string describing the set of elements with a given value for a string attribute. - [hascontextoption](https://www.sidefx.com/docs/houdini/expressions/hascontextoption.html) Returns a non-zero value if the specified context option exists. - [hasdetailattrib](https://www.sidefx.com/docs/houdini/expressions/hasdetailattrib.html) Returns 1 if a specified detail attribute exists. - [haspdgattrib](https://www.sidefx.com/docs/houdini/expressions/haspdgattrib.html) Returns 1 if the active PDG work item has the specified attribute. - [haspoint](https://www.sidefx.com/docs/houdini/expressions/haspoint.html) Returns 1 if a specified point is in a specified group. - [haspointattrib](https://www.sidefx.com/docs/houdini/expressions/haspointattrib.html) Returns 1 if a specified point attribute exists. - [hasprim](https://www.sidefx.com/docs/houdini/expressions/hasprim.html) Returns 1 if a specified primitive is in a specified group. - [hasprimattrib](https://www.sidefx.com/docs/houdini/expressions/hasprimattrib.html) Returns 1 if a specified primitive attribute exists. - [hasvertexattrib](https://www.sidefx.com/docs/houdini/expressions/hasvertexattrib.html) Returns 1 if a specified vertex attribute exists. - [hextoint](https://www.sidefx.com/docs/houdini/expressions/hextoint.html) Converts a hexadecimal argument string into an integer. - [hsv](https://www.sidefx.com/docs/houdini/expressions/hsv.html) Converts RGB values to HSV components. - [ic](https://www.sidefx.com/docs/houdini/expressions/ic.html) Evaluates a CHOP’s input channel at a specific index. - [ice](https://www.sidefx.com/docs/houdini/expressions/ice.html) Returns the end index of a CHOP’s input. - [icl](https://www.sidefx.com/docs/houdini/expressions/icl.html) Returns the length of a CHOP’s input, in samples. - [icmax](https://www.sidefx.com/docs/houdini/expressions/icmax.html) Evaluates a CHOP’s input channel’s maximum value. - [icmin](https://www.sidefx.com/docs/houdini/expressions/icmin.html) Evaluates a CHOP’s input channel’s minimum value. - [icn](https://www.sidefx.com/docs/houdini/expressions/icn.html) Returns the number of channels in a CHOP’s input. - [icr](https://www.sidefx.com/docs/houdini/expressions/icr.html) Returns the sample rate of a CHOP’s input. - [ics](https://www.sidefx.com/docs/houdini/expressions/ics.html) Returns the start index of a CHOP’s input. - [identity](https://www.sidefx.com/docs/houdini/expressions/identity.html) Creates an identity matrix. - [if](https://www.sidefx.com/docs/houdini/expressions/if.html) Returns the value of the second or third argument depending on the truth of the first argument. - [ifs](https://www.sidefx.com/docs/houdini/expressions/ifs.html) Returns the string value of the second or third argument depending on the truth of the first argument. - [index](https://www.sidefx.com/docs/houdini/expressions/index_.html) Finds the first occurrence of a pattern in a string. - [instancepoint](https://www.sidefx.com/docs/houdini/expressions/instancepoint.html) Returns the point number currently being instanced onto. - [int](https://www.sidefx.com/docs/houdini/expressions/int.html) Converts a number to an integer by truncating any fractional part. - [inttohex](https://www.sidefx.com/docs/houdini/expressions/inttohex.html) Converts a number into a hexadecimal string. - [invert](https://www.sidefx.com/docs/houdini/expressions/invert.html) Inverts a matrix. - [iprquery](https://www.sidefx.com/docs/houdini/expressions/iprquery.html) Queries numeric (floating point) data from an interactive render pane. - [iprquerys](https://www.sidefx.com/docs/houdini/expressions/iprquerys.html) Queries textual (string) data from an interactive render pane. - [isclosed](https://www.sidefx.com/docs/houdini/expressions/isclosed.html) Returns 1 if a primitive is closed. - [iscollided](https://www.sidefx.com/docs/houdini/expressions/iscollided.html) Returns 1 if a specified point has collided with something. - [ishvariable](https://www.sidefx.com/docs/houdini/expressions/ishvariable.html) Returns 1 if a specified Houdini environment variable exists. - [ispdgeval](https://www.sidefx.com/docs/houdini/expressions/ispdgeval.html) Returns 1 if the parameter is being evaluated as part of a PDG cook, else 0 - [isspline](https://www.sidefx.com/docs/houdini/expressions/isspline.html) Returns 1 if a specified primitive is a NURBs or Bezier curve or surface. - [isstuck](https://www.sidefx.com/docs/houdini/expressions/isstuck.html) Returns 1 if a specified point is a stuck particle. - [isvariable](https://www.sidefx.com/docs/houdini/expressions/isvariable.html) Returns 1 if a specified Houdini or system environment variable exists. - [iswrapu](https://www.sidefx.com/docs/houdini/expressions/iswrapu.html) Returns 1 if a specified primitive is wrapped in U. - [iswrapv](https://www.sidefx.com/docs/houdini/expressions/iswrapv.html) Returns 1 if a specified primitive is wrapped in V. - [length](https://www.sidefx.com/docs/houdini/expressions/length.html) Returns the length of a vector. - [linear](https://www.sidefx.com/docs/houdini/expressions/linear.html) Channel segment function: linear interpolation. - [listbyval](https://www.sidefx.com/docs/houdini/expressions/listbyval.html) Returns a list of elements with a given value for an integer attribute. - [listbyvals](https://www.sidefx.com/docs/houdini/expressions/listbyvals.html) Returns a list of elements with a given value for a string attribute. - [lock](https://www.sidefx.com/docs/houdini/expressions/lock.html) Returns a value that cannot be changed. - [log](https://www.sidefx.com/docs/houdini/expressions/log.html) Returns the natural logarithm of the argument. - [log10](https://www.sidefx.com/docs/houdini/expressions/log10.html) Returns the base 10 logarithm of the argument. - [lopinputprim](https://www.sidefx.com/docs/houdini/expressions/lopinputprim.html) Returns the path of the USD primitive last modified by an input to a LOP node. - [lopinputprims](https://www.sidefx.com/docs/houdini/expressions/lopinputprims.html) Returns the paths of the USD primitives last modified by an input to a LOP node. - [loplastmodifiedprim](https://www.sidefx.com/docs/houdini/expressions/loplastmodifiedprim.html) Returns the path of the USD primitive last modified by a LOP node. - [loplastmodifiedprims](https://www.sidefx.com/docs/houdini/expressions/loplastmodifiedprims.html) Returns the paths of the USD primitives last modified by a LOP node. - [lopparentprims](https://www.sidefx.com/docs/houdini/expressions/lopparentprims.html) Returns the paths of the parents of the supplied list of USD primitives. - [loprelativeprims](https://www.sidefx.com/docs/houdini/expressions/loprelativeprims.html) Returns the paths at a particular location relative to the supplied list of USD primitives. - [ltrim](https://www.sidefx.com/docs/houdini/expressions/ltrim.html) Trims white sapce from the front of a string. - [match](https://www.sidefx.com/docs/houdini/expressions/match.html) Channel segment function: matches the incoming and outgoing values. - [matchin](https://www.sidefx.com/docs/houdini/expressions/matchin.html) Channel segment function: matches the incoming slope. - [matchout](https://www.sidefx.com/docs/houdini/expressions/matchout.html) Channel segment function: matches the outgoing slope. - [matrix](https://www.sidefx.com/docs/houdini/expressions/matrix.html) Converts a string specification into a matrix. - [matrixtoquat](https://www.sidefx.com/docs/houdini/expressions/matrixtoquat.html) Converts a rotation matrix to a quaternion. - [max](https://www.sidefx.com/docs/houdini/expressions/max.html) Returns the larger of two values. - [mcols](https://www.sidefx.com/docs/houdini/expressions/mcols.html) Returns the number of columns in a matrix. - [metaweight](https://www.sidefx.com/docs/houdini/expressions/metaweight.html) Returns the weight of a metaball at a specific location. - [min](https://www.sidefx.com/docs/houdini/expressions/min.html) Returns the smaller of two values. - [mindist](https://www.sidefx.com/docs/houdini/expressions/mindist.html) Finds the smallest distance between a point and a primitive. - [mlookat](https://www.sidefx.com/docs/houdini/expressions/mlookat.html) Computes the transformation matrix of a lookat from one vector to another. - [mlookatup](https://www.sidefx.com/docs/houdini/expressions/mlookatup.html) Computes the transformation matrix of a lookat from one vector to another, with an up vector. - [mobjlookat](https://www.sidefx.com/docs/houdini/expressions/mobjlookat.html) Computes the transformation matrix of a lookat from one object to another. - [modblend](https://www.sidefx.com/docs/houdini/expressions/modblend.html) Blends the two modular values. - [morient](https://www.sidefx.com/docs/houdini/expressions/morient.html) Computes the transformation matrix to orient along specific Z and Y axes. - [mousepane](https://www.sidefx.com/docs/houdini/expressions/mousepane.html) Returns the full name of the pane currently under the mouse pointer. - [mousepath](https://www.sidefx.com/docs/houdini/expressions/mousepath.html) Returns the node path of the pane currently under the mouse pointer. - [mrows](https://www.sidefx.com/docs/houdini/expressions/mrows.html) Returns the number of rows in a matrix. - [mzero](https://www.sidefx.com/docs/houdini/expressions/mzero.html) Returns a matrix with all values set to 0. - [nearpoint](https://www.sidefx.com/docs/houdini/expressions/nearpoint.html) Finds the point in a geometry nearest to specific 3D coordinates. - [noise](https://www.sidefx.com/docs/houdini/expressions/noise.html) Generates 3D noise. - [normal](https://www.sidefx.com/docs/houdini/expressions/normal.html) Returns the components of the surface normal specific UV coordinates. - [normalize](https://www.sidefx.com/docs/houdini/expressions/normalize.html) Normalizes a vector. - [npoints](https://www.sidefx.com/docs/houdini/expressions/npoints.html) Returns the number of points in a geometry. - [npointsgroup](https://www.sidefx.com/docs/houdini/expressions/npointsgroup.html) Returns the number of points in the specified group. - [nprims](https://www.sidefx.com/docs/houdini/expressions/nprims.html) Returns the number of primitives in a surface node. - [nprimsgroup](https://www.sidefx.com/docs/houdini/expressions/nprimsgroup.html) Returns the number of primitives in the specified group. - [nuniquevals](https://www.sidefx.com/docs/houdini/expressions/nuniquevals.html) Returns the number of unique values for an integer or string attribute in a surface node. - [nvertices](https://www.sidefx.com/docs/houdini/expressions/nvertices.html) Returns the number of vertices in a geometry. - [nverticesgroup](https://www.sidefx.com/docs/houdini/expressions/nverticesgroup.html) Returns the number of vertices in the specified group. - [objkinoverride](https://www.sidefx.com/docs/houdini/expressions/objkinoverride.html) Returns the current global kinematic override setting for bone objects. - [objlightmask](https://www.sidefx.com/docs/houdini/expressions/objlightmask.html) Returns a list of lights matching an object’s light mask. - [objlookat](https://www.sidefx.com/docs/houdini/expressions/objlookat.html) Computes the rotation vector of a lookat from one object to another. - [objpretransform](https://www.sidefx.com/docs/houdini/expressions/objpretransform.html) Returns an object’s pre-transform matrix. - [oc](https://www.sidefx.com/docs/houdini/expressions/oc.html) Returns the value of a CHOP’s output at a specific sample index. - [ocldeviceinfo](https://www.sidefx.com/docs/houdini/expressions/ocldeviceinfo.html) Queries the current OpenCL device with the provided flag - [oldrand](https://www.sidefx.com/docs/houdini/expressions/oldrand.html) Returns a pseudo-random number between 0 and 1. - [opblist](https://www.sidefx.com/docs/houdini/expressions/opblist.html) Returns the full paths of all operators in a bundle. - [opcreator](https://www.sidefx.com/docs/houdini/expressions/opcreator.html) Returns the creator of this node. - [opdigits](https://www.sidefx.com/docs/houdini/expressions/opdigits.html) Returns the numeric suffix of a node name. - [opexist](https://www.sidefx.com/docs/houdini/expressions/opexist.html) Returns 1 if the specified node, group, or bundle exists. - [opflag](https://www.sidefx.com/docs/houdini/expressions/opflag.html) Returns a list nodes with a particular flag set. - [opfullpath](https://www.sidefx.com/docs/houdini/expressions/opfullpath.html) Returns the full path of a node. - [opfullpathfrom](https://www.sidefx.com/docs/houdini/expressions/opfullpathfrom.html) Returns the path of a node relative to another node. - [opid](https://www.sidefx.com/docs/houdini/expressions/opid.html) Returns the unique ID of a node. - [opinput](https://www.sidefx.com/docs/houdini/expressions/opinput.html) Returns the name of the node connected to a given input. - [opinputpath](https://www.sidefx.com/docs/houdini/expressions/opinputpath.html) Returns the full path of the node connected to a given input. - [opinputstring](https://www.sidefx.com/docs/houdini/expressions/opinputstring.html) Returns the value associated with a key string on node connection. - [opisloading](https://www.sidefx.com/docs/houdini/expressions/opisloading.html) Returns 1 if Houdini is currently loading a scene file. - [opisquitting](https://www.sidefx.com/docs/houdini/expressions/opisquitting.html) Returns 1 if Houdini is currently shutting down. - [oplightmask](https://www.sidefx.com/docs/houdini/expressions/oplightmask.html) Returns a list of lights matching an object’s light mask. - [oplistsort](https://www.sidefx.com/docs/houdini/expressions/oplistsort.html) Sorts a list of node paths based on node input/outputs order. - [opname](https://www.sidefx.com/docs/houdini/expressions/opname.html) Returns the name of a node given its path. - [opnchildren](https://www.sidefx.com/docs/houdini/expressions/opnchildren.html) Returns the number of nodes inside a container node. - [opninputs](https://www.sidefx.com/docs/houdini/expressions/opninputs.html) Returns the maximum number of connected inputs. - [opnodigits](https://www.sidefx.com/docs/houdini/expressions/opnodigits.html) Returns the alphanumeric prefix of a node name eliminating trailing digits. - [opnoutputs](https://www.sidefx.com/docs/houdini/expressions/opnoutputs.html) Returns the number of nodes connected to a node’s output. - [opoutput](https://www.sidefx.com/docs/houdini/expressions/opoutput.html) Returns the name of a node connected a given node’s output. - [opoutputpath](https://www.sidefx.com/docs/houdini/expressions/opoutputpath.html) Returns the full path of a node connected a given node’s output. - [oppinput](https://www.sidefx.com/docs/houdini/expressions/oppinput.html) Deprecated: replaced by opinput. - [oppwd](https://www.sidefx.com/docs/houdini/expressions/oppwd.html) Returns the path of the current network. - [oppwf](https://www.sidefx.com/docs/houdini/expressions/oppwf.html) Prints the path of the current network. - [oprelativepath](https://www.sidefx.com/docs/houdini/expressions/oprelativepath.html) Returns the relative path from one node to another. - [opselect](https://www.sidefx.com/docs/houdini/expressions/opselect.html) Returns a list of the selected nodes. - [opselectpath](https://www.sidefx.com/docs/houdini/expressions/opselectpath.html) Returns a list of the full paths of selected nodes. - [opselectrecurse](https://www.sidefx.com/docs/houdini/expressions/opselectrecurse.html) Returns a recursive list of the selected nodes. - [opselectrecursepath](https://www.sidefx.com/docs/houdini/expressions/opselectrecursepath.html) Returns a recursive list of the full paths of selected nodes. - [opstreamname](https://www.sidefx.com/docs/houdini/expressions/opstreamname.html) Computes the active stream of a node. - [opsubpath](https://www.sidefx.com/docs/houdini/expressions/opsubpath.html) Returns the full path of a node including any containing subnets. - [optransform](https://www.sidefx.com/docs/houdini/expressions/optransform.html) Returns the transformation matrix of an object at the current time. - [optype](https://www.sidefx.com/docs/houdini/expressions/optype.html) Returns the type of a node. - [optypeinfo](https://www.sidefx.com/docs/houdini/expressions/optypeinfo.html) Returns type information about a node. - [origin](https://www.sidefx.com/docs/houdini/expressions/origin.html) Returns components of an object’s transforms. - [originoffset](https://www.sidefx.com/docs/houdini/expressions/originoffset.html) Returns components of an object’s offset transforms. - [padzero](https://www.sidefx.com/docs/houdini/expressions/padzero.html) Returns a string padding a number to a given length with zeros. - [param](https://www.sidefx.com/docs/houdini/expressions/param.html) Deprecated: use stamp instead. - [parmisstring](https://www.sidefx.com/docs/houdini/expressions/parmisstring.html) Returns 1 if a specified parameter is a string. - [pdgattrib](https://www.sidefx.com/docs/houdini/expressions/pdgattrib.html) Returns the value of a PDG work item attrib - [pdgattriblist](https://www.sidefx.com/docs/houdini/expressions/pdgattriblist.html) Returns a space-separated list of attribute names on the active PDG work item. - [pdgattribs](https://www.sidefx.com/docs/houdini/expressions/pdgattribs.html) Returns the string value of a PDG work item attribute - [pdgattribsize](https://www.sidefx.com/docs/houdini/expressions/pdgattribsize.html) Returns the number of components in a PDG work item attribute. - [pdgattribtype](https://www.sidefx.com/docs/houdini/expressions/pdgattribtype.html) Returns the type of a PDG work item attribute. - [pdgattribute](https://www.sidefx.com/docs/houdini/expressions/pdgattribute.html) Deprecated: replaced by pdgattrib. - [pdgattributes](https://www.sidefx.com/docs/houdini/expressions/pdgattributes.html) Deprecated: replaced by pdgattribs. - [pdgattribvals](https://www.sidefx.com/docs/houdini/expressions/pdgattribvals.html) Returns the space separated list of values for a PDG work item attribute - [pdginput](https://www.sidefx.com/docs/houdini/expressions/pdginput.html) Returns a work item input file for the specified file index and tag - [pdginputsize](https://www.sidefx.com/docs/houdini/expressions/pdginputsize.html) Returns the number of input files on the active PDG work item - [pdginputtag](https://www.sidefx.com/docs/houdini/expressions/pdginputtag.html) Returns the file tag for the input file at the specified index. - [pdginputvals](https://www.sidefx.com/docs/houdini/expressions/pdginputvals.html) Returns a space separated string of all work item input files for the specified tag - [pdgmappath](https://www.sidefx.com/docs/houdini/expressions/pdgmappath.html) Maps the given path to the local Zone - [pdgoutput](https://www.sidefx.com/docs/houdini/expressions/pdgoutput.html) Returns a work item output file for the specified file index and tag - [pdgoutputsize](https://www.sidefx.com/docs/houdini/expressions/pdgoutputsize.html) Returns the number of output files on the active PDG work item - [pdgoutputtag](https://www.sidefx.com/docs/houdini/expressions/pdgoutputtag.html) Returns the file tag for the output file at the specified index. - [pdgoutputvals](https://www.sidefx.com/docs/houdini/expressions/pdgoutputvals.html) Returns a space separated string of all work item output files for the specified tag - [pic](https://www.sidefx.com/docs/houdini/expressions/pic.html) Returns the color of a pixel in a compositing node. - [picni](https://www.sidefx.com/docs/houdini/expressions/picni.html) Returns the non-interpolated color of a pixel in a compositing node. - [pluralize](https://www.sidefx.com/docs/houdini/expressions/pluralize.html) Converts an English noun to its plural. - [point](https://www.sidefx.com/docs/houdini/expressions/point.html) Returns the value of a point attribute. - [pointattriblist](https://www.sidefx.com/docs/houdini/expressions/pointattriblist.html) Returns a space-separated list of point attribute names. - [pointattribsize](https://www.sidefx.com/docs/houdini/expressions/pointattribsize.html) Returns the number of components in a point attribute. - [pointattribtype](https://www.sidefx.com/docs/houdini/expressions/pointattribtype.html) Returns the type of a point attribute. - [pointavg](https://www.sidefx.com/docs/houdini/expressions/pointavg.html) Returns the average of an attribute across all points in a geometry. - [pointdist](https://www.sidefx.com/docs/houdini/expressions/pointdist.html) Returns the distance between a point and a primitive. - [pointgrouplist](https://www.sidefx.com/docs/houdini/expressions/pointgrouplist.html) Returns the list of point groups in a surface node. - [pointgroupmask](https://www.sidefx.com/docs/houdini/expressions/pointgroupmask.html) Returns the list of point groups matching a pattern in a surface node. - [pointlist](https://www.sidefx.com/docs/houdini/expressions/pointlist.html) Returns a list of all points in a point group. - [pointneighbours](https://www.sidefx.com/docs/houdini/expressions/pointneighbours.html) Lists points that share a minimum number of primitives with a specified point. - [pointpattern](https://www.sidefx.com/docs/houdini/expressions/pointpattern.html) Returns a list of points that match a specified pattern. - [points](https://www.sidefx.com/docs/houdini/expressions/points.html) Returns the string value of a point attribute. - [pointsmap](https://www.sidefx.com/docs/houdini/expressions/pointsmap.html) Returns a string from a list of strings in a point attribute. - [pointsnummap](https://www.sidefx.com/docs/houdini/expressions/pointsnummap.html) Returns the number of unique strings bound to a point attribute. - [pointvals](https://www.sidefx.com/docs/houdini/expressions/pointvals.html) Returns components of a string array attribute. - [pow](https://www.sidefx.com/docs/houdini/expressions/pow.html) Raises a number to an exponent. - [prim](https://www.sidefx.com/docs/houdini/expressions/prim.html) Returns the value of a primitive attribute. - [primattriblist](https://www.sidefx.com/docs/houdini/expressions/primattriblist.html) Returns a space-separated list of primitive attribute names. - [primattribsize](https://www.sidefx.com/docs/houdini/expressions/primattribsize.html) Returns the number of components in a primitive attribute. - [primattribtype](https://www.sidefx.com/docs/houdini/expressions/primattribtype.html) Returns the type of a primitive attribute. - [primdist](https://www.sidefx.com/docs/houdini/expressions/primdist.html) Returns the minimum distance and closest points between two primitives. - [primduv](https://www.sidefx.com/docs/houdini/expressions/primduv.html) Returns the partial derivatives of a primitive attribute. - [primgrouplist](https://www.sidefx.com/docs/houdini/expressions/primgrouplist.html) Returns the list of primitive groups in a surface node. - [primgroupmask](https://www.sidefx.com/docs/houdini/expressions/primgroupmask.html) Returns the list of groups matching a pattern in a surface node. - [primlist](https://www.sidefx.com/docs/houdini/expressions/primlist.html) Returns a list of all primitives in a surface node. - [primneighbours](https://www.sidefx.com/docs/houdini/expressions/primneighbours.html) Lists primitives that share a minimum number of points with a specified primitive. - [prims](https://www.sidefx.com/docs/houdini/expressions/prims.html) Returns the string value of a primitive attribute. - [primsmap](https://www.sidefx.com/docs/houdini/expressions/primsmap.html) Returns a string from a list of strings in a primitive attribute. - [primsnummap](https://www.sidefx.com/docs/houdini/expressions/primsnummap.html) Returns the number of unique strings bound to a primitive attribute. - [primuv](https://www.sidefx.com/docs/houdini/expressions/primuv.html) Returns the value of a primitive attribute at a certain UV location. - [primvals](https://www.sidefx.com/docs/houdini/expressions/primvals.html) Returns components of a string array attribute. - [print](https://www.sidefx.com/docs/houdini/expressions/print.html) Prints a message to the console. - [property](https://www.sidefx.com/docs/houdini/expressions/property.html) Similar to ch(), but for render properties, with a default if the property doesn’t exist. - [propertyf](https://www.sidefx.com/docs/houdini/expressions/propertyf.html) Evaluates a render property at a given frame. - [propertys](https://www.sidefx.com/docs/houdini/expressions/propertys.html) Evaluates the string value of a render property at the current time. - [propertysop](https://www.sidefx.com/docs/houdini/expressions/propertysop.html) Evaluates a render property at the current time as a node path string. - [propertysraw](https://www.sidefx.com/docs/houdini/expressions/propertysraw.html) Evaluates the raw (unexpanded) string value of a render property at the current time. - [propertyt](https://www.sidefx.com/docs/houdini/expressions/propertyt.html) Evaluates a render property at a given time. - [pulse](https://www.sidefx.com/docs/houdini/expressions/pulse.html) Returns 1 when a value is within a certain range. - [pythonexprf](https://www.sidefx.com/docs/houdini/expressions/pythonexprf.html) Evaluates a Python expression, returning a float result. - [pythonexprs](https://www.sidefx.com/docs/houdini/expressions/pythonexprs.html) Evaluates a Python expression, returning a string result. - [qlinear](https://www.sidefx.com/docs/houdini/expressions/qlinear.html) Channel segment function: uses quaternions to interpolate. - [quattomatrix](https://www.sidefx.com/docs/houdini/expressions/quattomatrix.html) Converts quaternion to a 3×3 rotation matrix. - [quintic](https://www.sidefx.com/docs/houdini/expressions/quintic.html) Channel segment function: smoothly interpolates slopes and accelerations. - [rad](https://www.sidefx.com/docs/houdini/expressions/rad.html) Converts from degrees to radians. - [rand](https://www.sidefx.com/docs/houdini/expressions/rand.html) Returns a pseudo-random number from 0 to 1. - [raw](https://www.sidefx.com/docs/houdini/expressions/raw.html) Channel segment function. - [realuv](https://www.sidefx.com/docs/houdini/expressions/realuv.html) Converts unit UV to real UV. - [relpath](https://www.sidefx.com/docs/houdini/expressions/relpath.html) Returns the relative path of a file. - [repeat](https://www.sidefx.com/docs/houdini/expressions/repeat.html) Channel segment function: repeats animation from previous frames. - [repeatt](https://www.sidefx.com/docs/houdini/expressions/repeatt.html) Channel segment function: repeats animation from previous frames. - [res](https://www.sidefx.com/docs/houdini/expressions/res.html) Returns the natural resolution of the image in a compositing node. - [rgb](https://www.sidefx.com/docs/houdini/expressions/rgb.html) Converts HSV values to RGB components. - [rindex](https://www.sidefx.com/docs/houdini/expressions/rindex.html) Finds the last occurrence of a pattern in a string. - [rint](https://www.sidefx.com/docs/houdini/expressions/rint.html) Rounds to the nearest integer. - [rotate](https://www.sidefx.com/docs/houdini/expressions/rotate.html) Returns a 4×4 rotation matrix from an axis and angle. - [rotaxis](https://www.sidefx.com/docs/houdini/expressions/rotaxis.html) Returns a 4×4 rotation matrix from an angle and a vector. - [round](https://www.sidefx.com/docs/houdini/expressions/round.html) Rounds a number to the nearest integer. - [rtrim](https://www.sidefx.com/docs/houdini/expressions/rtrim.html) Trims white sapce from the end of a string. - [run](https://www.sidefx.com/docs/houdini/expressions/run.html) Runs a string as an HScript command and returns the command’s output. - [runb](https://www.sidefx.com/docs/houdini/expressions/runb.html) Runs a string as an HScript command and returns the command and error output. - [rune](https://www.sidefx.com/docs/houdini/expressions/rune.html) Runs a string as an HScript command and returns any error output. - [scale](https://www.sidefx.com/docs/houdini/expressions/scale.html) Takes three scaling values and returns a scale matrix. - [scalefrommks](https://www.sidefx.com/docs/houdini/expressions/scalefrommks.html) Returns the scale factor converting from MKS units to the Houdini units. - [scaletomks](https://www.sidefx.com/docs/houdini/expressions/scaletomks.html) Returns the scale factor converting to MKS units from the Houdini units. - [seampoints](https://www.sidefx.com/docs/houdini/expressions/seampoints.html) Lists all seam points in a surface node. - [seqanim](https://www.sidefx.com/docs/houdini/expressions/seqanim.html) Returns 1 if a specified compositing node has an animated sequence. - [seqend](https://www.sidefx.com/docs/houdini/expressions/seqend.html) Returns the end frame of a compositing node’s image sequence. - [seqlength](https://www.sidefx.com/docs/houdini/expressions/seqlength.html) Returns the number of frames in a compositing node’s image sequence. - [seqstart](https://www.sidefx.com/docs/houdini/expressions/seqstart.html) Returns the start frame of a compositing node’s image sequence. - [shopstring](https://www.sidefx.com/docs/houdini/expressions/shopstring.html) Returns the shader string generated by a shader. - [sign](https://www.sidefx.com/docs/houdini/expressions/sign.html) Returns -1, 0, or 1 depending on the sign of the argument. - [sin](https://www.sidefx.com/docs/houdini/expressions/sin.html) Returns the sine of the argument. - [sinh](https://www.sidefx.com/docs/houdini/expressions/sinh.html) Returns the hyperbolic sine of the argument. - [smooth](https://www.sidefx.com/docs/houdini/expressions/smooth.html) Takes a value and range and returns a smooth interpolation between 0 and 1. - [snoise](https://www.sidefx.com/docs/houdini/expressions/snoise.html) Generates sparse convolution 3D noise. - [spknot](https://www.sidefx.com/docs/houdini/expressions/spknot.html) Returns a knot value on a spline curve or surface. - [spline](https://www.sidefx.com/docs/houdini/expressions/spline.html) Channel segment function: fits a curve to the keyframes. - [sqrt](https://www.sidefx.com/docs/houdini/expressions/sqrt.html) Returns the square root of the argument. - [stamp](https://www.sidefx.com/docs/houdini/expressions/stamp.html) Returns a copy stamping floating point value. - [stamps](https://www.sidefx.com/docs/houdini/expressions/stamps.html) Returns a copy stamping string value. - [strcasecmp](https://www.sidefx.com/docs/houdini/expressions/strcasecmp.html) Compares two strings, ignoring case. - [strcasematch](https://www.sidefx.com/docs/houdini/expressions/strcasematch.html) Returns 1 if a string matches a pattern, ignoring case. - [strcat](https://www.sidefx.com/docs/houdini/expressions/strcat.html) Returns the concatenation of two strings. - [strcmp](https://www.sidefx.com/docs/houdini/expressions/strcmp.html) Compares two strings. - [strdup](https://www.sidefx.com/docs/houdini/expressions/strdup.html) Duplicates a string. - [stripmatrix](https://www.sidefx.com/docs/houdini/expressions/stripmatrix.html) Strips non-essential characters from the string representation of a matrix or vector. - [strlen](https://www.sidefx.com/docs/houdini/expressions/strlen.html) Returns the number of characters in a string. - [strmatch](https://www.sidefx.com/docs/houdini/expressions/strmatch.html) Returns 1 if a string matches a pattern, including case. - [strreplace](https://www.sidefx.com/docs/houdini/expressions/strreplace.html) Replaces substrings with a new string. - [strsplit](https://www.sidefx.com/docs/houdini/expressions/strsplit.html) Returns one component of a string split by some separators. - [strsplitcount](https://www.sidefx.com/docs/houdini/expressions/strsplitcount.html) Returns the number of components in a string split by some separators. - [sturb](https://www.sidefx.com/docs/houdini/expressions/sturb.html) Generates spatially coherent 3D noise based on sparse convolution. - [substr](https://www.sidefx.com/docs/houdini/expressions/substr.html) Returns a substring of a string. - [surflen](https://www.sidefx.com/docs/houdini/expressions/surflen.html) Returns the length of the 3D curve between two points on a surface. - [system](https://www.sidefx.com/docs/houdini/expressions/system.html) Runs a system command line and returns the output. - [systemES](https://www.sidefx.com/docs/houdini/expressions/systemES.html) Runs a system command line and returns the exit status. - [systemRAW](https://www.sidefx.com/docs/houdini/expressions/systemRAW.html) Runs a system command line and returns the output with no processing. - [tan](https://www.sidefx.com/docs/houdini/expressions/tan.html) Returns the tangent of the argument. - [tanh](https://www.sidefx.com/docs/houdini/expressions/tanh.html) Returns the hyperbolic tangent of the argument. - [tex](https://www.sidefx.com/docs/houdini/expressions/tex.html) Returns the interpolated color of a point on an on-disk texture map. - [texni](https://www.sidefx.com/docs/houdini/expressions/texni.html) Returns the non-interpolated color of a point on an on-disk texture map. - [tolower](https://www.sidefx.com/docs/houdini/expressions/tolower.html) Returns the all-lowercase version of a string. - [toupper](https://www.sidefx.com/docs/houdini/expressions/toupper.html) Returns the all-uppercase version of a string. - [translate](https://www.sidefx.com/docs/houdini/expressions/translate.html) Takes X, Y, and Z translation values and returns a translation matrix. - [transpose](https://www.sidefx.com/docs/houdini/expressions/transpose.html) Transposes a matrix. - [trim](https://www.sidefx.com/docs/houdini/expressions/trim.html) Trims white sapce from either side of a string. - [trunc](https://www.sidefx.com/docs/houdini/expressions/trunc.html) Converts a number to an integer by truncating any fractional part, rounding towards 0. - [turb](https://www.sidefx.com/docs/houdini/expressions/turb.html) Generates spatially coherent 3D noise. - [uniqueval](https://www.sidefx.com/docs/houdini/expressions/uniqueval.html) Returns a unique value of an integer attribute. - [uniquevals](https://www.sidefx.com/docs/houdini/expressions/uniquevals.html) Returns a unique value of a string attribute. - [unituv](https://www.sidefx.com/docs/houdini/expressions/unituv.html) Converts real UV to unit UV. - [uvdist](https://www.sidefx.com/docs/houdini/expressions/uvdist.html) Returns the distance between parameteric locations on two primitives. - [vangle](https://www.sidefx.com/docs/houdini/expressions/vangle.html) Returns the angle between two vectors. - [vector](https://www.sidefx.com/docs/houdini/expressions/vector.html) Converts a string specification into a vector. - [vector3](https://www.sidefx.com/docs/houdini/expressions/vector3.html) Converts three values into a 3-component vector. - [vector4](https://www.sidefx.com/docs/houdini/expressions/vector4.html) Converts four values into a 4-component vector. - [vertex](https://www.sidefx.com/docs/houdini/expressions/vertex.html) Returns the value of a vertex attribute. - [vertexattriblist](https://www.sidefx.com/docs/houdini/expressions/vertexattriblist.html) Returns a space-separated list of vertex attribute names. - [vertexattribsize](https://www.sidefx.com/docs/houdini/expressions/vertexattribsize.html) Returns the number of components in a vertex attribute. - [vertexattribtype](https://www.sidefx.com/docs/houdini/expressions/vertexattribtype.html) Returns the type of a vertex attribute. - [vertexgrouplist](https://www.sidefx.com/docs/houdini/expressions/vertexgrouplist.html) Returns the list of vertex groups in a surface node. - [vertexgroupmask](https://www.sidefx.com/docs/houdini/expressions/vertexgroupmask.html) Returns the list of vertex groups matching a pattern in a surface node. - [vertexs](https://www.sidefx.com/docs/houdini/expressions/vertexs.html) Returns the string value of a vertex attribute. - [vertexsmap](https://www.sidefx.com/docs/houdini/expressions/vertexsmap.html) Returns a string from a list of strings in a vertex attribute. - [vertexsnummap](https://www.sidefx.com/docs/houdini/expressions/vertexsnummap.html) Returns the number of unique strings bound to a point attribute. - [vertexvals](https://www.sidefx.com/docs/houdini/expressions/vertexvals.html) Returns components of a string array attribute. - [vlength](https://www.sidefx.com/docs/houdini/expressions/vlength.html) Returns the length of a vector. - [vlength2](https://www.sidefx.com/docs/houdini/expressions/vlength2.html) - [vmatch](https://www.sidefx.com/docs/houdini/expressions/vmatch.html) Channel segment function: matches the incoming and outgoing slopes. - [vmatchin](https://www.sidefx.com/docs/houdini/expressions/vmatchin.html) Channel segment function: matches the incoming slope. - [vmatchout](https://www.sidefx.com/docs/houdini/expressions/vmatchout.html) Channel segment function: matches the outgoing slope. - [volumeaverage](https://www.sidefx.com/docs/houdini/expressions/volumeaverage.html) Returns the average value of all the voxels in a volume. - [volumegradient](https://www.sidefx.com/docs/houdini/expressions/volumegradient.html) Returns the gradient of a volume primitive at a specified location. - [volumeindex](https://www.sidefx.com/docs/houdini/expressions/volumeindex.html) Returns the value of a volume primitive at a specified voxel. - [volumeindextopos](https://www.sidefx.com/docs/houdini/expressions/volumeindextopos.html) Converts volume voxel coordinates to world-space coordinates. - [volumemax](https://www.sidefx.com/docs/houdini/expressions/volumemax.html) Returns the maximum value of all voxels in a volume. - [volumemin](https://www.sidefx.com/docs/houdini/expressions/volumemin.html) Returns the minimum value of all voxels in a volume. - [volumepostoindex](https://www.sidefx.com/docs/houdini/expressions/volumepostoindex.html) Converts world space coordinates to volume voxel coordinates. - [volumeres](https://www.sidefx.com/docs/houdini/expressions/volumeres.html) Returns the resolution of a volume. - [volumesample](https://www.sidefx.com/docs/houdini/expressions/volumesample.html) Returns the value of a volume at a specified position. - [volumevoxeldiameter](https://www.sidefx.com/docs/houdini/expressions/volumevoxeldiameter.html) Returns the approximage diameter of a volume voxel in world space. - [vorigin](https://www.sidefx.com/docs/houdini/expressions/vorigin.html) Returns a vector of an objects' transforms. - [vpname](https://www.sidefx.com/docs/houdini/expressions/vpname.html) Takes a viewer name and a viewport number and returns the viewport’s name. - [vrorigin](https://www.sidefx.com/docs/houdini/expressions/vrorigin.html) Returns a vector of an object’s rotations. - [vscale](https://www.sidefx.com/docs/houdini/expressions/vscale.html) Multiplies a vector by a scaling factor. - [vset](https://www.sidefx.com/docs/houdini/expressions/vset.html) Creates a vector with each component set to the same value. - [vsize](https://www.sidefx.com/docs/houdini/expressions/vsize.html) Returns the number of elements in a vector. - [vtorigin](https://www.sidefx.com/docs/houdini/expressions/vtorigin.html) Returns a vector of an object’s translations. - [wrap](https://www.sidefx.com/docs/houdini/expressions/wrap.html) Wraps a value between a minimum and maximum. - [xyzdist](https://www.sidefx.com/docs/houdini/expressions/xyzdist.html) Returns the distance between a 3D coordinate and a primitive.