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/* Test smoothness scaling behaviour for 2D */
#include <stdio.h>
#include <math.h>
double trans(double *v, int luord, double vv);
double f(double x, double y) {
double fp[2][5] = {
{ 1.0, 0.7, -0.3, 0.0, 0.0 },
{ 1.0, 0.7, -0.3, 0.0, 0.0 }
};
double v;
#ifdef NEVER
/* 1D function */
v = trans(fp[0], 5, x);
#else
/* 1D on angle */
v = trans(fp[0], 5, 0.5 * (x+y));
v *= 2.0 * sqrt(2.0); // ?????
#endif
// v = trans(fp[0], 5, x)
// + trans(fp[0], 5, y);
return v;
}
int main() {
double min = 0.0;
double max = 1.0;
int di = 2;
int i, res = 4;
#define LOC(xx) (min + (max-min) * (xx)/(res-1.0))
/* For each resolution */
for (i = 0; i < 10; i++, res *= 2) {
double tse = 0.0; /* Total squared error */
int j, k;
/* For each grid point with neigbors */
for (j = 1; j < (res-1); j++) {
for (k = 1; k < (res-1); k++) {
double err;
double y1, y2, y3;
y1 = f(LOC(j-1), LOC(k));
y2 = f(LOC(j+0), LOC(k));
y3 = f(LOC(j+1), LOC(k));
err = 0.5 * (y3 + y1) - y2;
tse += err * err;
// tse += fabs(err);
y1 = f(LOC(j), LOC(k-1));
y2 = f(LOC(j), LOC(k+0));
y3 = f(LOC(j), LOC(k+1));
err = 0.5 * (y3 + y1) - y2;
tse += err * err;
// tse += fabs(err);
}
}
/* Apply adjustments and corrections */
tse *= pow((res-1.0), 4.0); /* Aprox. geometric resolution factor */
tse /= pow((res-2.0),(double)di); /* Average squared non-smoothness */
// tse /= (di * pow((res-2.0),(double)di)); /* Average squared non-smoothness */
printf("Res %d, tse = %f\n",res,tse);
}
return 0;
}
/* Transfer function */
double trans(
double *v, /* Pointer to first parameter */
int luord, /* Number of parameters */
double vv /* Source of value */
) {
double g;
int ord;
for (ord = 0; ord < luord; ord++) {
int nsec; /* Number of sections */
double sec; /* Section */
g = v[ord]; /* Parameter */
nsec = ord + 1; /* Increase sections for each order */
vv *= (double)nsec;
sec = floor(vv);
if (((int)sec) & 1)
g = -g; /* Alternate action in each section */
vv -= sec;
if (g >= 0.0) {
vv = vv/(g - g * vv + 1.0);
} else {
vv = (vv - g * vv)/(1.0 - g * vv);
}
vv += sec;
vv /= (double)nsec;
}
return vv;
}
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