HPUX CrtMathFnc[3]

 Tcl_CreateMathFunc(3)               Tcl               Tcl_CreateMathFunc(3)

 Tcl Library Procedures                               Tcl Library Procedures

                                     7.0



 ___________________________________________________________________________

 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
                                             function will be defined.

      char            *name        (in)      Name for new function.

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

      Tcl_ValueType   *argTypes    (in)      Points to an array  giving  the
                                             permissible   types   for  each
                                             argument 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.
 ___________________________________________________________________________


 DESCRIPTION
      Tcl  allows  a  number  of  mathematical  functions  to  be  used   in
      expressions,  such  as sin, cos, and hypot.  Tcl_CreateMathFunc allows
      applications 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 function then a new function is created.  If it does exist,
      then the existing 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
      corresponding 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:



                                    - 1 -        Formatted:  August 11, 1996






 Tcl_CreateMathFunc(3)               Tcl               Tcl_CreateMathFunc(3)

 Tcl Library Procedures                               Tcl Library Procedures

                                     7.0



           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
      arguments to the function:
           typedef struct Tcl_Value {
                Tcl_ValueType type;
                int 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 interp->result.


 KEYWORDS
      expression, mathematical function


















                                    - 2 -        Formatted:  August 11, 1996