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Tcl_CreateMathFunc(3)		      Tcl Library Procedures		    Tcl_CreateMathFunc(3)

_________________________________________________________________________________________________

NAME
       Tcl_CreateMathFunc,  Tcl_GetMathFuncInfo,  Tcl_ListMathFuncs - Define, query and enumerate
       math functions for expressions

SYNOPSIS
       #include <tcl.h>

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

       int
       Tcl_GetMathFuncInfo(interp, name, numArgsPtr, argTypesPtr, procPtr,
			   clientDataPtr)

       Tcl_Obj *
       Tcl_ListMathFuncs(interp, pattern)

ARGUMENTS
       Tcl_Interp *interp (in)			  Interpreter  in  which  new  function  will  be
						  defined.

       const 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.

       int *numArgsPtr (out)			  Points to a variable that will be set  to  con-
						  tain the number of arguments to the function.

       Tcl_ValueType **argTypesPtr (out)	  Points  to  a variable that will be set to con-
						  tain a pointer to an array giving the permissi-
						  ble  types  for  each  argument to the function
						  which will need to be freed up using Tcl_Free.

       Tcl_MathProc **procPtr (out)		  Points to a variable that will be set  to  con-
						  tain	a  pointer to the implementation code for
						  the function (or NULL if the function is imple-
						  mented directly in bytecode).

       ClientData *clientDataPtr (out)		  Points  to  a variable that will be set to con-
						  tain the clientData argument passed to Tcl_Cre-
						  ateMathFunc  when  the  function was created if
						  the function is  not	implemented  directly  in
						  bytecode.

       const char *pattern (in) 		  Pattern  to  match against function names so as
						  to filter them (by passing to Tcl_StringMatch),
						  or NULL to not apply any filter.
_________________________________________________________________

DESCRIPTION
       Tcl allows a number of mathematical functions to be used in expressions, such as sin, cos,
       and hypot.  These functions are represented by commands in the  namespace,  tcl::mathfunc.
       The  Tcl_CreateMathFunc	function  is  an  obsolete way for applications to add additional
       functions to those already provided by Tcl or to replace existing  functions.   It  should
       not  be	used by new applications, which should create math functions using Tcl_CreateObj-
       Command to create a command in the tcl::mathfunc namespace.

       In the Tcl_CreateMathFunc interface, Name is the name of the function as it will appear in
       expressions.   If name does not already exist in the ::tcl::mathfunc namespace, then a new
       command is created in that namespace.  If name 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 one of TCL_INT, TCL_DOUBLE, TCL_WIDE_INT, or TCL_EITHER to indicate
       whether	the corresponding argument must be an integer, a double-precision floating value,
       a wide (64-bit) integer, or any, 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 arguments to the function:
	      typedef struct Tcl_Value {
		      Tcl_ValueType type;
		      long intValue;
		      double doubleValue;
		      Tcl_WideInt wideValue;
	      } Tcl_Value;

       The  type  field  indicates  the type of the argument and is one of TCL_INT, TCL_DOUBLE or
       TCL_WIDE_INT.  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, doubleValue or wideValue 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 one
       of TCL_INT, TCL_DOUBLE or TCL_WIDE_INT to indicate which value was set.	Under normal cir-
       cumstances  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.

       Tcl_GetMathFuncInfo retrieves the values associated with function name that were passed to
       a preceding Tcl_CreateMathFunc call.  Normally, the return code is TCL_OK but if the named
       function does not exist, TCL_ERROR is returned and an  error  message  is  placed  in  the
       interpreter's result.

       If  an  error  did  not	occur,	the  array reference placed in the variable pointed to by
       argTypesPtr is newly allocated, and should be released by passing it  to  Tcl_Free.   Some
       functions (the standard set implemented in the core, and those defined by placing commands
       in the tcl::mathfunc namespace) do not  have  argument  type  information;  attempting  to
       retrieve  values for them causes a NULL to be stored in the variable pointed to by procPtr
       and the variable pointed to by clientDataPtr will not be modified.  The	variable  pointed
       to by numArgsPointer will contain -1, and no argument types will be stored in the variable
       pointed to by argTypesPointer.

       Tcl_ListMathFuncs returns a Tcl object containing a list of all the math functions defined
       in  the interpreter whose name matches pattern.	The returned object has a reference count
       of zero.

SEE ALSO
       expr(n), info(n), Tcl_CreateObjCommand(3), Tcl_Free(3), Tcl_NewListObj(3)

KEYWORDS
       expression, mathematical function

Tcl					       8.4			    Tcl_CreateMathFunc(3)
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