Tcl_CreateMathFunc

Tcl_CreateMathFunc(3)       Tcl Library Procedures       Tcl_CreateMathFunc(3)



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NAME
       Tcl_CreateMathFunc - Define a new math function for expressions

SYNOPSIS
       #include <tcl.h>

       Tcl_CreateMathFunc(interp, name, numArgs, argTypes, proc, clientData)

ARGUMENTS
       Tcl_Interp      *interp      (in)      Interpreter  in  which new func-
                                              tion will be defined.

       char            *name        (in)      Name for new function.

       int             numArgs      (in)      Number of arguments to new func-
                                              tion;    also   gives   size  of
                                              argTypes array.

       Tcl_ValueType   *argTypes    (in)      Points to an  array  giving  the
                                              permissible types for each argu-
                                              ment to function.

       Tcl_MathProc    *proc        (in)      Procedure  that  implements  the
                                              function.

       ClientData      clientData   (in)      Arbitrary one-word value to pass
                                              to proc when it is invoked.
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DESCRIPTION
       Tcl allows a number of mathematical functions to  be  used  in  expres-
       sions, such as sin, cos, and hypot.  Tcl_CreateMathFunc allows applica-
       tions to add additional functions to those already provided by  Tcl  or
       to  replace existing functions.  Name is the name of the function as it
       will appear in expressions.  If name doesn't already exist as  a  func-
       tion then a new function is created.  If it does exist, then the exist-
       ing function is replaced.  NumArgs and argTypes describe the  arguments
       to  the  function.   Each  entry  in  the argTypes array must be either
       TCL_INT, TCL_DOUBLE, or TCL_EITHER to indicate whether the  correspond-
       ing  argument must be an integer, a double-precision floating value, or
       either, respectively.

       Whenever the function is invoked in an expression Tcl will invoke proc.
       Proc should have arguments and result that match the type Tcl_MathProc:
              typedef int Tcl_MathProc(
                ClientData clientData,
                Tcl_Interp *interp,
                Tcl_Value *args,
                Tcl_Value *resultPtr);

       When proc is invoked the clientData and interp arguments  will  be  the
       same  as  those  passed  to  Tcl_CreateMathFunc.  Args will point to an
       array of numArgs Tcl_Value structures, which describe the actual  argu-
       ments to the function:
              typedef struct Tcl_Value {
                Tcl_ValueType type;
                long intValue;
                double doubleValue;
              } Tcl_Value;

       The type field indicates the type of the argument and is either TCL_INT
       or TCL_DOUBLE.  It will match the  argTypes  value  specified  for  the
       function  unless  the  argTypes  value was TCL_EITHER. Tcl converts the
       argument supplied in the expression to the type requested in  argTypes,
       if  that  is  necessary.  Depending on the value of the type field, the
       intValue or doubleValue field will contain  the  actual  value  of  the
       argument.

       Proc  should  compute  its  result and store it either as an integer in
       resultPtr->intValue or as a floating value  in  resultPtr->doubleValue.
       It  should  set also resultPtr->type to either TCL_INT or TCL_DOUBLE to
       indicate which value was set.  Under normal circumstances  proc  should
       return  TCL_OK.   If an error occurs while executing the function, proc
       should return TCL_ERROR and leave an error message in the interpreter's
       result.


KEYWORDS
       expression, mathematical function



Tcl                                   7.0                Tcl_CreateMathFunc(3)