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/*
Explore.c
sample region, determine min and max, split if necessary
this file is part of Divonne
last modified 15 Nov 11 th
*/
typedef struct {
real fmin, fmax;
creal *xmin, *xmax;
} Extrema;
/*********************************************************************/
static int Explore(This *t, ccount iregion)
{
TYPEDEFREGION;
Region *region = RegionPtr(iregion);
cBounds *bounds = region->bounds;
Result *result = region->result;
count n, dim, comp, maxcomp;
Extrema extrema[NCOMP];
Result *r;
creal *x;
real *f;
real halfvol, maxerr;
cSamples *samples = &t->samples[region->isamples];
/* needed as of gcc 3.3 to make gcc correctly address region #@$&! */
sizeof(*region);
for( comp = 0; comp < t->ncomp; ++comp ) {
Extrema *e = &extrema[comp];
e->fmin = INFTY;
e->fmax = -INFTY;
e->xmin = e->xmax = NULL;
}
if( region->isamples == 0 ) { /* others already sampled */
real vol = 1;
for( dim = 0; dim < t->ndim; ++dim ) {
cBounds *b = &bounds[dim];
vol *= b->upper - b->lower;
}
region->vol = vol;
for( comp = 0; comp < t->ncomp; ++comp ) {
Result *r = &result[comp];
r->fmin = INFTY;
r->fmax = -INFTY;
}
x = t->xgiven;
f = t->fgiven;
n = t->ngiven;
if( t->nextra ) n += SampleExtra(t, bounds);
for( ; n; --n ) {
for( dim = 0; dim < t->ndim; ++dim ) {
cBounds *b = &bounds[dim];
if( x[dim] < b->lower || x[dim] > b->upper ) goto skip;
}
for( comp = 0; comp < t->ncomp; ++comp ) {
Extrema *e = &extrema[comp];
creal y = f[comp];
if( y < e->fmin ) e->fmin = y, e->xmin = x;
if( y > e->fmax ) e->fmax = y, e->xmax = x;
}
skip:
x += t->ldxgiven;
f += t->ncomp;
}
samples->sampler(t, iregion);
}
x = samples->x;
f = samples->f;
for( n = samples->n; n; --n ) {
for( comp = 0; comp < t->ncomp; ++comp ) {
Extrema *e = &extrema[comp];
creal y = *f++;
if( y < e->fmin ) e->fmin = y, e->xmin = x;
if( y > e->fmax ) e->fmax = y, e->xmax = x;
}
x += t->ndim;
}
t->neval_opt -= t->neval;
halfvol = .5*region->vol;
maxerr = -INFTY;
maxcomp = -1;
for( comp = 0; comp < t->ncomp; ++comp ) {
Extrema *e = &extrema[comp];
Result *r = &result[comp];
real xtmp[NDIM], ftmp, err;
if( e->xmin ) { /* not all NaNs */
t->selectedcomp = comp;
VecCopy(xtmp, e->xmin);
ftmp = FindMinimum(t, bounds, xtmp, e->fmin);
if( ftmp < r->fmin ) {
r->fmin = ftmp;
VecCopy(r->xmin, xtmp);
}
t->selectedcomp = Tag(comp);
VecCopy(xtmp, e->xmax);
ftmp = -FindMinimum(t, bounds, xtmp, -e->fmax);
if( ftmp > r->fmax ) {
r->fmax = ftmp;
VecCopy(r->xmax, xtmp);
}
}
r->spread = halfvol*(r->fmax - r->fmin);
err = r->spread/Max(fabs(r->avg), NOTZERO);
if( err > maxerr ) {
maxerr = err;
maxcomp = comp;
}
}
t->neval_opt += t->neval;
if( maxcomp == -1 ) { /* all NaNs */
region->depth = 0;
return -1;
}
region->cutcomp = maxcomp;
r = ®ion->result[maxcomp];
if( halfvol*(r->fmin + r->fmax) > r->avg ) {
region->fminor = r->fmin;
region->fmajor = r->fmax;
region->xmajor = r->xmax - (real *)region->result;
}
else {
region->fminor = r->fmax;
region->fmajor = r->fmin;
region->xmajor = r->xmin - (real *)region->result;
}
if( region->isamples == 0 ) {
if( r->spread < samples->neff*r->err ||
r->spread < t->totals[maxcomp].secondspread ) region->depth = 0;
if( region->depth == 0 )
for( comp = 0; comp < t->ncomp; ++comp )
t->totals[comp].secondspread =
Max(t->totals[comp].secondspread, result[comp].spread);
}
if( region->depth ) Split(t, iregion);
return iregion;
}
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