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Scilab Help >> API Scilab > legacy > Low level functions > Sparse matrix reading (Scilab gateway)

Sparse matrix reading (Scilab gateway)

How to read sparse matrices in a gateway.

Syntax

Input argument profile:

SciErr getSparseMatrix(void* _pvCtx, int* _piAddress, int* _piRows, int* _piCols, int* _piNbItem, int** _piNbItemRow, int** _piColPos, double** _pdblReal)
SciErr getComplexSparseMatrix(void* _pvCtx, int* _piAddress, int* _piRows, int* _piCols, int* _piNbItem, int** _piNbItemRow, int** _piColPos, double** _pdblReal, double** _pdblImg)

Named variable profile:

SciErr readNamedSparseMatrix(void* _pvCtx, const char* _pstName, int* _piRows, int* _piCols, int* _piNbItem, int* _piNbItemRow, int* _piColPos, double* _pdblReal)
SciErr readNamedComplexSparseMatrix(void* _pvCtx, const char* _pstName, int* _piRows, int* _piCols, int* _piNbItem, int* _piNbItemRow, int* _piColPos, double* _pdblReal, double* _pdblImg)

Arguments

_pvCtx

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

_piAddress

Address of the Scilab variable.

_pstName

Name of the variable for "named" functions.

_piRows

Return number of rows.

_piCols

Return number of columns.

_piNbItem

Return number of non zero value.

_piNbItemRow

Return number of item in each rows (size: _iRows).

_piColPos

Return column position for each item (size: _iNbItem).

_pdblReal

Return address of real data array (size: _iCols * _iRows) For "Named" function, _pdblReal must be allocated before calling function.

_pdblImg

Return address of imaginary data array (size: _iCols * _iRows) For "Named" function, _pdblImg must be allocated before calling function.

SciErr

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

Description

This help describes how sparse matrix can be handled through the Scilab API.

Gateway Source

#include "api_scilab.h"
int read_sparse(char *fname,void* pvApiCtx)
{
	SciErr sciErr;
	int i,j,k;
	int* piAddr			= NULL;
	int iRows			= 0;
	int iCols			= 0;
	int iNbItem			= 0;
	int* piNbItemRow	= NULL;
	int* piColPos		= NULL;
	double* pdblReal	= NULL;
	double* pdblImg		= NULL;

    CheckInputArgument(pvApiCtx, 1, 1);

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

	if(isVarComplex(pvApiCtx, piAddr))
	{
		sciErr = getComplexSparseMatrix(pvApiCtx, piAddr, &iRows, &iCols, &iNbItem, &piNbItemRow, &piColPos, &pdblReal, &pdblImg);
	}
	else
	{
		sciErr = getSparseMatrix(pvApiCtx, piAddr, &iRows, &iCols, &iNbItem, &piNbItemRow, &piColPos, &pdblReal);
	}

	if(sciErr.iErr)
	{
		printError(&sciErr, 0);
		return 0;
	}

	sciprint("Sparse %d item(s)\n", iNbItem);
	k = 0;

	for(i = 0 ; i < iRows ; i++)
	{
		for(j = 0 ; j < piNbItemRow[i] ; j++)
		{
			sciprint("(%d,%d) = %f", i+1, piColPos[k], pdblReal[k]);
			if(isVarComplex(pvApiCtx, piAddr))
			{
				sciprint(" %+fi", pdblImg[k]);
			}

			sciprint("\n");
			k++;
		}
	}

	//assign allocated variables to Lhs position
	AssignOutputVariable(pvApiCtx, 1) = 0;
	return 0;
}

Scilab test script

sp=sparse([1,2;4,5;3,10],[1 + 2*%i,2 - 3*%i,-3 + 4*%i]);
read_sparse(sp);
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