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factor.c
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factor.c
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// factor a polynomial or integer
#include "stdafx.h"
#include "defs.h"
void
eval_factor(void)
{
push(cadr(p1));
eval();
push(caddr(p1));
eval();
p2 = pop();
if (p2 == symbol(NIL))
guess();
else
push(p2);
factor();
// more factoring?
p1 = cdddr(p1);
while (iscons(p1)) {
push(car(p1));
eval();
factor_again();
p1 = cdr(p1);
}
}
void
factor_again(void)
{
int h, n;
save();
p2 = pop();
p1 = pop();
h = tos;
if (car(p1) == symbol(MULTIPLY)) {
p1 = cdr(p1);
while (iscons(p1)) {
push(car(p1));
push(p2);
factor_term();
p1 = cdr(p1);
}
} else {
push(p1);
push(p2);
factor_term();
}
n = tos - h;
if (n > 1)
multiply_all_noexpand(n);
restore();
}
void
factor_term(void)
{
save();
factorpoly();
p1 = pop();
if (car(p1) == symbol(MULTIPLY)) {
p1 = cdr(p1);
while (iscons(p1)) {
push(car(p1));
p1 = cdr(p1);
}
} else
push(p1);
restore();
}
void
factor(void)
{
save();
p2 = pop();
p1 = pop();
if (isinteger(p1)) {
push(p1);
factor_number(); // see pollard.cpp
} else {
push(p1);
push(p2);
factorpoly();
}
restore();
}
// for factoring small integers (2^32 or less)
void
factor_small_number(void)
{
int d, expo, i, n;
save();
n = pop_integer();
if (n == (int) 0x80000000)
stop("number too big to factor");
if (n < 0)
n = -n;
for (i = 0; i < MAXPRIMETAB; i++) {
d = primetab[i];
if (d > n / d)
break;
expo = 0;
while (n % d == 0) {
n /= d;
expo++;
}
if (expo) {
push_integer(d);
push_integer(expo);
}
}
if (n > 1) {
push_integer(n);
push_integer(1);
}
restore();
}