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begin branch to replace qhull with voro++ for tessellation

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Paul M. Sutter 2025-06-28 12:19:33 -04:00
parent be797c05dc
commit 53483fd0d8
11 changed files with 1449 additions and 1 deletions
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81
c_source/vorozobov/findrtop.c Normal file
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#include <math.h>
#include <stdlib.h>
/*------------------------------------------------------------------------------
Find nb elements of Real array a having the largest value.
Returns index iord of these elements, ordered so iord[0] corresponds
to element a[iord[0]] having the largest value.
If nb > na, then the last nb-na elements of iord are undefined.
Elements of a that are equal are left in their original order.
Courtesy Andrew Hamilton.
*/
void findrtop(double *a, int na, int *iord, int nb)
{
#undef ORDER
#define ORDER(ia, ja) a[ia] > a[ja] || (a[ia] == a[ja] && ia < ja)
int i, ia, ib, it, n;
n = (na <= nb)? na : nb;
if (n <= 0) return;
/* heap first n elements, so smallest element is at top of heap */
for (ib = (n >> 1); ib < n; ib++) {
iord[ib] = ib;
}
for (ia = (n >> 1) - 1; ia >= 0; ia--) {
i = ia;
for (ib = (i << 1) + 1; ib < n; ib = (i << 1) + 1) {
if (ib+1 < n) {
if (ORDER(iord[ib], iord[ib+1])) ib++;
}
if (ORDER(ia, iord[ib])) {
iord[i] = iord[ib];
i = ib;
} else {
break;
}
}
iord[i] = ia;
}
/* now compare rest of elements of array to heap */
for (ia = n; ia < na; ia++) {
/* if new element is greater than smallest, sift it into heap */
i = 0;
if (ORDER(ia, iord[i])) {
for (ib = (i << 1) + 1; ib < n; ib = (i << 1) + 1) {
if (ib+1 < n) {
if (ORDER(iord[ib], iord[ib+1])) ib++;
}
if (ORDER(ia, iord[ib])) {
iord[i] = iord[ib];
i = ib;
} else {
break;
}
}
iord[i] = ia;
}
}
/* unheap iord so largest element is at top */
for (ia = n - 1; ia > 0; ia--) {
it = iord[ia];
i = 0;
iord[ia] = iord[i];
for (ib = (i << 1) + 1; ib < ia; ib = (i << 1) + 1) {
if (ib+1 < ia) {
if (ORDER(iord[ib], iord[ib+1])) ib++;
}
if (ORDER(it, iord[ib])) {
iord[i] = iord[ib];
i = ib;
} else {
break;
}
}
iord[i] = it;
}
}