2.1.17.2.2.7 find_roots

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

Description

Find the points with specified height.

Syntax

int find_roots( const vector &vx, const vector &vy, vector &roots, double dBase = 0.0, vector<int> &vnDirection = NULL)

Parameters

vx: [input] X-coordinates of input points.
vy: [input] Y-coordinates of input points.
roots: [output] The collection holds all x at which the corresponding y equals to dBase
dBase: [input] The value used to get the collection of roots
vnDirection: [output] The direction of crossing; -1 for pos to neg; 0 for its derivative dy/dx = 0; 1 for neg to pos

Return

return the number of roots found, -1 if error occur.

Examples

EX1

void find_roots_ex1()
{
    //import data into new worksheet, user may import this data manully.
    LT_execute("win -t W Origin;");
    LT_execute("open -w %(system.path.program$)Samples\Curve Fitting\Gaussian.dat;");
    
    Worksheet wks = Project.ActiveLayer();
    if ( wks )
    {
        Column colX(wks, 0);
        Column colY(wks, 1);
        
        vector vX(colX);
        vector vY(colY);
        vector vRoots;
        int nSize = find_roots(vX, vY, vRoots, 5);
        if ( nSize > 0 )
        {
            ASSERT( vRoots.GetSize() == nSize );
            for ( int ii = 0; ii < nSize; ii++ )
                printf("vRoots[%d] = %lf\n", ii, vRoots[ii]);
        }
    }
}