2.1.17.8.9 ocmath_f_stretch

1 Description
2 Syntax
3 Parameters
4 Return
5 Examples
6 Remark
7 See Also
8 Header to Include
9 Reference

Description

Stretch (or squeeze) data in a vector or a matrix of type double by scaling all the data within a given range.

Syntax

int ocmath_f_stretch( float * pX, uint nSize, float low1, float high1, float low2, float high2 )

Parameters

pX: [modify] pointer to vector or matrix data
nSize: [input] size of vector, or nRows * nCols of a matrix
low1: [input] low value of the range of data to be scaled, for data < low1, they will become low2
high1: [input] high value of the range of data to be scaled, for data > high1, they will become high2
low2: [input] new low value of the data after the scaling
high2: [input] new high value of the data after the scaling

Return

FALSE if low1 == high1 which renders the operation impossible, otherwise returns TURE

Examples

EX1

// Create two identical matrices, use ocmath_d_stretch on one and plot both
void    ocmath_f_stretch_Ex1()
{
    MatrixPage        mp1;
    mp1.Create("origin", CREATE_VISIBLE);
    MatrixObject        mo1(mp1.GetName(), 0);
    LT_execute("matrix -v 50-abs(16.5-i)-abs(16.5-j);");

    MatrixPage        mp2;
    mp2.Create("origin", CREATE_VISIBLE);
    MatrixObject        mo2(mp2.GetName(), 0);
    LT_execute("matrix -v 50-abs(16.5-i)-abs(16.5-j);");

    matrix                mat;
    mat = mo1.GetDataObject();
    int                    nRows, nCols;
    mat.GetSourceDim(nRows, nCols);
    // Values in the range 25 to 35 will be squeezed into a range from 0 to 10
    // Values less than 25 become 0 and values greater than 35 become 10
    ocmath_d_stretch(mat, nRows * nCols, 25, 35, 0, 10);
    
    GraphPage        gp1;
    gp1.Create("cmap", CREATE_VISIBLE);
    GraphLayer        gl1(gp1.GetName());
    gl1.AddPlot(mo1, IDM_PLOT_SURFACE_COLORMAP);
    gl1.Rescale();

    GraphPage        gp2;
    gp2.Create("cmap", CREATE_VISIBLE);
    GraphLayer        gl2(gp2.GetName());
    gl2.AddPlot(mo2, IDM_PLOT_SURFACE_COLORMAP);
    gl2.Rescale();
}