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See the recommended documentation of this function

Справка Scilab >> API Scilab > Low level functions > Polynomial Symbolic Variable (Scilab gateway)

Polynomial Symbolic Variable (Scilab gateway)

How to get the symbolic variable name.

Calling Sequence

Input argument profile:

SciErr getPolyVariableName(void* _pvCtx, int* _piAddress, char* _pstVarName, int* _piVarNameLen)

Arguments

_pvCtx

Scilab environment pointer, pass in "pvApiCtx" provided by api_scilab.h.

_piAddress

Address of the variable.

_pstVarName

Return the symbolic varaible name

_piVarNameLen

Return the length of _pstVarName

SciErr

Error structure where is stored errors messages history and first error number.

Description

This help describes how to get the symbolic variable name.

Gateway Source

#include "api_scilab.h"
int read_poly(char *fname,unsigned long fname_len)
{
	SciErr sciErr;
	int i,j;
	//variable info
	int iRows			= 0;
	int iCols			= 0;
	int iVarLen			= 0;
	int* piAddr			= NULL;
	int* piNbCoef		= NULL;
	double** pdblReal	= NULL;
	double** pdblImg	= NULL;
	char* pstVarname	= NULL;

	//check input and output arguments
    CheckInputArgument(pvApiCtx, 1, 1);
    CheckOutputArgument(pvApiCtx, 1, 1);

	sciErr = getVarAddressFromPosition(pvApiCtx, 1, &piAddr);
	if(sciErr.iErr)
	{
		printError(&sciErr, 0);
		return 0;
	}

	if(isVarComplex(pvApiCtx, piAddr) == FALSE)
	{
		//Error
		return 0;
	}

	//get variable name length
	sciErr = getPolyVariableName(pvApiCtx, piAddr, NULL, &iVarLen);
	if(sciErr.iErr)
	{
		printError(&sciErr, 0);
		return 0;
	}

	//alloc buff to receive variable name
	pstVarname = (char*)malloc(sizeof(char) * (iVarLen + 1));//1 for null termination

	//get variable name
	sciErr = getPolyVariableName(pvApiCtx, piAddr, pstVarname, &iVarLen);
	if(sciErr.iErr)
	{
		printError(&sciErr, 0);
		return 0;
	}

	//First call: retrieve dimmension
	sciErr = getComplexMatrixOfPoly(pvApiCtx, piAddr, &iRows, &iCols, NULL, NULL, NULL);
	if(sciErr.iErr)
	{
		printError(&sciErr, 0);
		return 0;
	}

	//alloc array of coefficient
	piNbCoef = (int*)malloc(sizeof(int) * iRows * iCols);

	//Second call: retrieve coefficient
	sciErr = getComplexMatrixOfPoly(pvApiCtx, piAddr, &iRows, &iCols, piNbCoef, NULL, NULL);
	if(sciErr.iErr)
	{
		printError(&sciErr, 0);
		return 0;
	}

	//alloc arrays of data
	pdblReal    = (double**)malloc(sizeof(double*) * iRows * iCols);
	pdblImg     = (double**)malloc(sizeof(double*) * iRows * iCols);

	for(i = 0 ; i < iRows * iCols ; i++)
	{
		pdblReal[i] = (double*)malloc(sizeof(double) * piNbCoef[i]);
		pdblImg[i] = (double*)malloc(sizeof(double) * piNbCoef[i]);
	}

	//Third call: retrieve data
	sciErr = getComplexMatrixOfPoly(pvApiCtx, piAddr, &iRows, &iCols, piNbCoef, pdblReal, pdblImg);
	if(sciErr.iErr)
	{
		printError(&sciErr, 0);
		return 0;
	}

	//Do something with Data
	//Invert polynomials in the matrix and invert coefficients
	for(i = 0 ; i < (iRows * iCols) / 2 ; i++)
	{
		int iPos1			= iRows * iCols - 1 - i;
		double* pdblSave	= NULL;
		int iNbCoefSave		= 0;
		//switch array of coefficient
		pdblSave			= pdblReal[i];
		pdblReal[i]			= pdblReal[iPos1];
		pdblReal[iPos1]		= pdblSave;
		pdblSave			= pdblImg[i];
		pdblImg[i]			= pdblImg[iPos1];
		pdblImg[iPos1]		= pdblSave;
		//switch number of coefficient
		iNbCoefSave			= piNbCoef[i];
		piNbCoef[i]			= piNbCoef[iPos1];
		piNbCoef[iPos1]		= iNbCoefSave;
	}

	//switch coefficient
	for(i = 0 ; i < iRows * iCols ; i++)
	{
		for(j = 0 ; j < piNbCoef[i] /2 ; j++)
		{
			int iPos2			= piNbCoef[i] - 1 - j;
			double dblVal		= pdblReal[i][j];
			pdblReal[i][j]		= pdblReal[i][iPos2];
			pdblReal[i][iPos2]	= dblVal;
			dblVal				= pdblImg[i][j];
			pdblImg[i][j]		= pdblImg[i][iPos2];
			pdblImg[i][iPos2]	= dblVal;
		}
	}

	sciErr = createComplexMatrixOfPoly(pvApiCtx, nbInputArgument(pvApiCtx) + 1, pstVarname, iRows, iCols, piNbCoef, pdblReal, pdblImg);
	if(sciErr.iErr)
	{
		printError(&sciErr, 0);
		return 0;
	}

	//free OS memory
	free(pstVarname);
	free(piNbCoef);
	for(i = 0 ; i < iRows * iCols ; i++)
	{
		free(pdblReal[i]);
		free(pdblImg[i]);
	}
	free(pdblReal);
	free(pdblImg);
	//assign allocated variables to Lhs position
	AssignOutputVariable(pvApiCtx, 1) = nbInputArgument(pvApiCtx) + 1;
	return 0;
}

Scilab test script

coeff1 = [ ..
29*%i,22*%i,16*%i,11*%i,7*%i,30,23,17,12,8,-31*%i,-24*%i,-18*%i,-13*%i,-9*%i,32,25,19,14,10,-33*%i,-26*%i,-20*%i,-15*%i,0,34,27,21,0,0,0,-28*%i,0,0,0,36-35*%i,0,0,0,0; ..
4*%i,2*%i,%i,22,16,5,-3,0,-23*%i,-17*%i,-6*%i,0,0,24,18,0,0,0,-25*%i,-19*%i,0,0,0,26,20,0,0,0,-27*%i,-21*%i,0,0,0,28,0,0,0,0,0,0; ..
11,7,4,2,1,-12*%i,-8*%i,-5*%i,3*%i,0,13,9,6,0,0,-14*%i,-10*%i,0,0,0,15,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0];

x = poly(0, "x");
p1  = 1;
p2  = 2 * x + 3 * %i;
p3  = 4 * x**2 - 5 * %i * x + 6;
p4  = 7 * x**3 - 8 * %i * x**2 + 9 * x - 10 * %i;
p5  = 11 * x**4 - 12 * %i * x**3 + 13 * x**2 - 14 * %i * x + 15;
p6  = 16 * x**5 - 17 * %i * x**4 + 18 * x**3 - 19 * %i * x**2 + 20 * x  - 21 * %i;
p7  = 22 * x**6 - 23 * %i * x**5 + 24 * x**4 - 25 * %i * x**3 + 26 * x**2 - 27 * %i * x + 28;
p8  = %i;
p9  = 2 * %i * x - 3;
p10 = 4 * %i * x**2 + 5 * x - 6 * %i;
p11 = 7 * %i * x**3 + 8 * x**2 - 9 * %i * x + 10;
p12 = 11 * %i * x**4 + 12 * x**3 - 13 * %i * x**2 + 14 * x - 15 * %i;
p13 = 16 * %i * x**5 + 17 * x**4 - 18 * %i * x**3 + 19 * x**2 - 20 * %i * x  + 21;
p14 = 22 * %i * x**6 + 23 * x**5 - 24 * %i * x**4 + 25 * x**3 - 26 * %i * x**2 + 27 * x - 28 * %i;
p15 = 29 * %i * x**7 + 30 * x**6 - 31 * %i * x**5 + 32 * x**4 - 33 * %i * x**3 + 34 * x**2 - 35 * %i + 36;
p = [p1, p2, p3, p4, p5 ; p6, p7, p8, p9 ,p10 ; p11, p12, p13, p14, p15];

p1 = read_poly(p);
coeff2 = coeff(p1);
if or(coeff2 <> coeff1) then error("failed"), end
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Last updated:
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