simulacion-permeabilidad/fftma_module/gen/lib_src/maxfactor.c

#include "genlib.h"

/*determines the greatest prime factor of an integer*/
int maxfactor(int n)
{
    int test_fact(int* pnum, int fact, int* pmaxfac);
    int lnum, fact;
    int maxfac;

    maxfac = 1;
    lnum = n;

    if (lnum != 0 && lnum != 1) {
        fact = 2;
        if (test_fact(&lnum, fact, &maxfac)) {
            fact = 3;
            if (test_fact(&lnum, fact, &maxfac)) {
                fact = 5;
                for (;;) {
                    if (!test_fact(&lnum, fact, &maxfac))
                        break;
                    fact += 2;
                    if (!test_fact(&lnum, fact, &maxfac))
                        break;
                    fact += 4;
                }
            }
        }
        if (lnum != 1) {
            if (lnum > maxfac)
                maxfac = lnum;
        }
    }
    return (maxfac);
}