OriginC: Interpolation and Gridding

XYZ Gridding by Renka Cline Method(Origin80 SR0)

#include <Origin.h>
#include <OC_nag.h>
int xyz_gridding_in_renka_cline(const vector& vx, const vector& vy, const vector& vz, 
                                const vector& vxGrid, const vector& vyGrid, matrix& mat) 
{
        Nag_Scat_Struct  comm;
        NagError  fail;
        //INIT_FAIL
        fail.code = NE_NOERROR;
        fail.print = 0;

        int nSize = vx.GetSize();
        vector<int> triang(7*nSize);
        vector<double> grads(2*nSize);
        int nRows = mat.GetNumRows();
        int nCols = mat.GetNumCols();
        //nag_2d_scat_interpolan
        //nag_2d_scat_interpolant (e01sac) has been replaced by nag_2d_triang_interp (e01sjc) at Mark 25
        e01sjc(nSize, vx, vy, vz, triang, grads, &fail);
        if (fail.code != NE_NOERROR)
        {
                printf("Error from e01sjc: %s\n", fail.message);
                return fail.code;
        }
        //nag_2d_scat_eval
        //nag_2d_scat_eval (e01sbc) has been replaced by nag_2d_triang_eval (e01skc) at Mark 25   
        for(int ii=0; ii < nRows; ii++)
        {
                for(int jj=0; jj < nCols; jj++)
                {
                        e01skc(nSize,vx, vy, vz, triang, grads, vxGrid[jj], vyGrid[ii], &mat[jj][ii], &fail);
                }
        }
        if (fail.code != NE_NOERROR && fail.code != NW_VALUE_EXTRAPOLATED)
        {
                printf("Error from e01skc: %s\n", fail.message);
                return fail.code;
        }
        
        return OE_NOERROR; 
}

1d Spline and NAG_FREE(Origin80 SR4)

#include <Origin.h>
#include <OC_nag.h> // must include this to see nag related macros and prototypes

// to run this example, you need to have 4 columns in the active
// worksheet and fill col(A) with a few rows by row number and col(B) by same
// number of rows of random values.
// This function will generate results in col(C) and col(D)
void test_e01bac(int nX = 0, int nY = 1, int nXFit = 2, int nYFit = 3)
{
        Worksheet wks = Project.ActiveLayer();
        // the knots in nX and nY
        Dataset aa(wks, nX);
        Dataset bb(wks, nY);
        vector vx, vy;
        vx = aa;
        vy = bb;
        Nag_Spline spline;
        int m = vx.GetSize();
        NagError fail = {0};
        e01bac(m, vx, vy, &spline, &fail);
        printf("Number of distinct knots = %d\n", m-2);
        printf("Distinct knots located at\n");
        for(int j = 3; j <m+1; j++)
                printf("%8.4f%s", spline.lamda[j], (j-3)%5==4 || j==m? "\n":" ");
        printf("\n\n   J B-spline coeff c\n\n");
        for(j=0; j <m; j++)
                printf("\n   %d  %13.4f\n", j+1, spline.c[j]);

        // put fit into col(nYFit) from x=col(nXFit)
        Dataset fitx(wks, nXFit);
        Dataset fity(wks, nYFit);
        // generate the X from original X by using each mid point, so total m-1 new points
        fitx.SetSize(m-1);
        for(int ii = 0; ii < m - 1; ii++)
                fitx[ii] = (aa[ii] + aa[ii+1]) * 0.5;
        //now we can get the spline fit
        fity.SetSize(fitx.GetSize());
        for(j=0; j<fity.GetSize(); j++)
        {
                double yy = NANUM;
                NagError fail = {0};
                e02bbc(fitx[j], &yy, &spline, &fail);
                fity[j] = yy;
        }
        //Free memory allocated by e01bac
        NAG_FREE(spline.lamda);
        NAG_FREE(spline.c);
}