XSLPcalluserfunc
XSLPcalluserfunc |
Purpose
Call a user function from a program or from within another user function
Synopsis
double XPRS_CC XSLPcalluserfunc(XSLPprob Prob, int FuncNumber, void *Arg1, void *Arg2, void *Arg3, void *Arg4, void *Arg5, void *Arg6)
Arguments
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Prob
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The current SLP problem.
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FuncNumber
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The internal number of the function to be called.
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Arg1
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address of an array of double precision values holding the input values for the function. May be
NULL if not required.
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Arg2
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address of an array of integer values. This must be dimensioned at least
XSLP_FUNCINFOSIZE and is normally populated by using
XSLPsetuserfuncinfo. This array must always be provided, even if the user function does not use it.
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Arg3
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address of a string buffer, normally used to hold the names of the input variables. May be
NULL if not required.
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Arg4
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address of a string buffer, normally used to hold the names of the return variables. May be
NULL if not required.
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Arg5
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address of an array of double precision values, normally used to hold the array of perturbations or flags for calculating first derivatives. May be
NULL if not required.
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Arg6
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address of an array of double precision values, used to hold the array of return values from the function. This argument can always be provided and, if not null, will be used to hold the return value(s) from the function. May be
NULL if not required.
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Return value
If the called function returns a single value, the return value of
XSLPcalluserfunc is the called function value; if the called function returns the address of array of values, the return value of
XSLPcalluserfunc is the value of the first item in the array.
Example
The following example sets up the data to call user function number 2 with three input values, and prints the first return value from the function.
double InputArray[3], ReturnArray[4];
double FuncInfo[XSLP_FUNCINFOSIZE];
InputArray[0] = 1.42; InputArray[1] = 5;
InputArray[2] = -99;
XSLPsetuserfuncinfo(Prob, FuncInfo, 0, 3, 1, 0, 0, 0);
XSLPcalluserfunc(Prob, 2, InputArray, FuncInfo,
NULL, NULL, NULL, ReturnArray);
printf("Result = %lg\n",ReturnArray[0]);
Further information
Apart from Arg2 (which is always required) and Arg6 (which will always be used if it is provided), any argument required by the function must not be NULL. So, for example, if the function expects an array of input names then Arg3 must be provided.
It is the user's responsibility to ensure that any arrays used are large enough to hold the data.
The function is provided as a means to call user functions in a uniform way; e.g. this allows for calling functions defined as external from the API (like Excel macros).
Related topics