static void do_stuff(void)
{
//int m = 7;
int m = 3;
int n = 3;
double a[n*m], d[n], u[m*m], v[n*n], dmat[n*m];
// build and print a matrix of random numbers
FORI(n*m) a[i] = randombounds(10, 99);
PMATRIX(a, m, n);
// compute the SVD
int r = svd(d, a, u, m, v, n);
// show the results
FORI(n*m) dmat[i] = 0;
FORI(n) dmat[n*i+i] = d[i];
PMATRIX(dmat, m, n);
PMATRIX(u, m, m);
PMATRIX(v, n, n);
// check the reconstruction
double ud[m*n], udv[m*n];
rmmult(ud, u, dmat, m, m, n);
trnm(v,n);
rmmult(udv, ud, v, m, n, n);
PMATRIX(udv, m, n);
}
// fisher-yates
void shuffle(void *t, int n, size_t s)
{
char *c = t;
for (int i = 0; i < n-1; i++)
swap(c + s*i, c + s*randombounds(i, n-1), s);
}
int randombounds(int a, int b)
{
if (b < a)
return randombounds(b, a);
if (b == a)
return b;
return a + rand()%(b - a + 1);
}
static int randombounds(int a, int b)
{
if (b < a)
return randombounds(b, a);
if (b == a)
return b;
return a + lcg_knuth_rand() % (b - a + 1);
}
static float float_pick(float *x, int n)
{
if (n) {
int i = randombounds(0, n-1);
return x[i];
}
else
fail("empty list of pixel values!");
}
static void statistics_getf_spoilable(struct statistics_float *s, float *f,
int n)
{
s->middle = f[n/2-1];
int mt = STATISTIC_MEDIAN_BIAS;
int mi = STATISTIC_MIDDLE_BIAS;
switch(mi)
{
case -1: break;
case 0: s->middle += f[n/2]; s->middle /=2; break;
case 1: s->middle = f[n/2]; break;
default: error("bad STATISTIC_MEDIAN_BIAS %d", mt);
}
//
qsort(f, n, sizeof*f, compare_floats);
s->min = f[0];
s->max = f[n-1];
s->median = f[n/2-1];
if (EVENP(n))
{
int mtype = STATISTIC_MEDIAN_BIAS;
switch(mtype)
{
case -1: break;
case 0: s->median += f[n/2]; s->median /=2; break;
case 1: s->median = f[n/2]; break;
default: error("bad STATISTIC_MEDIAN_BIAS %d", mtype);
}
}
s->average = 0;
for (int i = 0; i < n; i++)
s->average += f[i];
s->average /= n;
s->laverage = 0;
for (int i = 0; i < n; i++)
s->laverage += exp(f[i]/255);
s->laverage = log(s->laverage/n)*255;
s->variance = 0;
for (int i = 0; i < n; i++)
s->variance = hypot(s->variance, s->average - f[i]);
s->sample = f[randombounds(0, n-1)];
}
float op_random(float* data, int N){
return data[randombounds(0, N-1)];
}
