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Scilab manual >> API Scilab > Low level functions > Double reading (Scilab gateway)

Double reading (Scilab gateway)

How to read matrices of double in a gateway.

Calling Sequence

Input argument profile:

SciErr getMatrixOfDouble(void* _pvCtx, int* _piAddress, int* _piRows, int* _piCols, double** _pdblReal)
SciErr getComplexMatrixOfDouble(void* _pvCtx, int* _piAddress, int* _piRows, int* _piCols, double** _pdblReal, double** _pdblImg)

Named variable profile:

SciErr readNamedMatrixOfDouble(void* _pvCtx, const char* _pstName, int* _piRows, int* _piCols, double* _pdblReal)
SciErr readNamedComplexMatrixOfDouble(void* _pvCtx, const char* _pstName, int* _piRows, int* _piCols, 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.

_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 matrix of doubles can be handled through the Scilab API.

Gateway Source

int read_double(char *fname,unsigned long fname_len)
{
    int i;
    //first variable info : real matrix of double
    int iType            = 0;
    int iRows            = 0;
    int iCols            = 0;
    int iComplex        = 0;
    int *piAddr            = NULL;
    double* pdblReal    = NULL;
    double* pdblImg        = NULL;

    SciErr sciErr;
    //check input and output arguments
    CheckRhs(1,1);
    CheckLhs(1,1);

    /************************
    *    First variable    *
    ************************/

    //get variable address of the first input argument
    sciErr = getVarAddressFromPosition(pvApiCtx, 1, &piAddr);
    if(sciErr.iErr)
    {
        printError(&sciErr, 0);
        return 0;
    }

    //check type
    sciErr = getVarType(pvApiCtx, piAddr, &iType);
    if(sciErr.iErr || iType != sci_matrix)
    {
        printError(&sciErr, 0);
        return 0;
    }

    //get complexity
    iComplex    = isVarComplex(pvApiCtx, piAddr);

    //check complexity
    if(iComplex)
    {
        //get size and data from Scilab memory
        sciErr = getComplexMatrixOfDouble(pvApiCtx, piAddr, &iRows, &iCols, &pdblReal, &pdblImg);
    }
    else
    {
        //get size and data from Scilab memory
        sciErr = getMatrixOfDouble(pvApiCtx, piAddr, &iRows, &iCols, &pdblReal);
    }

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

    //Do something with data
    //if variable is complex, switch real part and imaginary part otherwise multiply by -1

    if(iComplex)
    {
        sciErr = createComplexMatrixOfDouble(pvApiCtx, Rhs + 1, iRows, iCols, pdblImg, pdblReal);
    }
    else
    {
        for(i = 0 ; i < iRows * iCols ; i++)
        {
            pdblReal[i] = pdblReal[i] * -1;
        }
        sciErr = createMatrixOfDouble(pvApiCtx, Rhs + 1, iRows, iCols, pdblReal);
    }

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

    LhsVar(1) = Rhs + 1;
    return 0;
}

Scilab test script

a = [   0 1 2 3; ..
        4 5 6 7; ..
        8 9 10 11];
b = [   23*%i,      1+22*%i,    2+21*%i,    3+20*%i,    4+19*%i,    5+18*%i; ..
        6+17*%i,    7+16*%i,    8+15*%i,    9+14*%i,     10+13*%i,  11+12*%i; ..
        12+11*%i,   13+10*%i,   14+9*%i,    15+8*%i,    16+7*%i,    17+6*%i; ..
        18+5*%i,    19+4*%i,    20+3*%i,    21+2*%i,    22+1*%i,    23];

a2 = read_double(a);
b2 = read_double(b);

if or(a2 <> a * -1) then error("failed"), end
if or(b2 <> (imag(b) + real(b) * %i)) then error("failed"), end
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with contributors 		Last updated:
Wed Jan 26 16:25:14 CET 2011