Application: gvSIG desktop

/* generate double bivariate Chebychev polynomial */

#ifndef lint

static const char SCCSID[]="@(#)bchgen.c        4.5        94/03/22        GIE        REL";

#endif

#include <projects.h>

        int

bchgen(projUV a, projUV b, int nu, int nv, projUV **f, projUV(*func)(projUV)) {

        int i, j, k;

        projUV arg, *t, bma, bpa, *c;

        double d, fac;

        bma.u = 0.5 * (b.u - a.u); bma.v = 0.5 * (b.v - a.v);

        bpa.u = 0.5 * (b.u + a.u); bpa.v = 0.5 * (b.v + a.v);

        for ( i = 0; i < nu; ++i) {

                arg.u = cos(PI * (i + 0.5) / nu) * bma.u + bpa.u;

                for ( j = 0; j < nv; ++j) {

                        arg.v = cos(PI * (j + 0.5) / nv) * bma.v + bpa.v;

                        f[i][j] = (*func)(arg);

                        if ((f[i][j]).u == HUGE_VAL)

                                return(1);

                }

        }

        if (!(c = (projUV *) vector1(nu, sizeof(projUV)))) return 1;

        fac = 2. / nu;

        for ( j = 0; j < nv ; ++j) {

                for ( i = 0; i < nu; ++i) {

                        arg.u = arg.v = 0.;

                        for (k = 0; k < nu; ++k) {

                                d = cos(PI * i * (k + .5) / nu);

                                arg.u += f[k][j].u * d;

                                arg.v += f[k][j].v * d;

                        }

                        arg.u *= fac;

                        arg.v *= fac;

                        c[i] = arg;

                }

                for (i = 0; i < nu; ++i)

                        f[i][j] = c[i];

        }

        pj_dalloc(c);

        if (!(c = (projUV*) vector1(nv, sizeof(projUV)))) return 1;

        fac = 2. / nv;

        for ( i = 0; i < nu; ++i) {

                t = f[i];

                for (j = 0; j < nv; ++j) {

                        arg.u = arg.v = 0.;

                        for (k = 0; k < nv; ++k) {

                                d = cos(PI * j * (k + .5) / nv);

                                arg.u += t[k].u * d;

                                arg.v += t[k].v * d;

                        }

                        arg.u *= fac;

                        arg.v *= fac;

                        c[j] = arg;

                }

                f[i] = c;

                c = t;

        }

        pj_dalloc(c);

        return(0);

}