eigenmath/factor.cpp

143 lines
1.8 KiB
C++

#include "stdafx.h"
#include "defs.h"
void
eval_factor(void)
{
push(cadr(p1));
eval();
if (isinteger(stack[tos - 1])) {
factor_number(); // see pollard.cpp
return;
}
p1 = cddr(p1);
push(car(p1));
eval();
factorpoly(); // factorpoly handles omitted 2nd arg (2nd arg = nil)
p1 = cdr(p1);
while (iscons(p1)) {
push(car(p1));
eval();
factorpoly();
p1 = cdr(p1);
}
}
// 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();
}
static char *s[] = {
"factor(0)",
"0",
"factor(1)",
"1",
"factor(2)",
"2",
"factor(3)",
"3",
"factor(4)",
"2^2",
"factor(5)",
"5",
"factor(6)",
"2*3",
"factor(7)",
"7",
"factor(8)",
"2^3",
"factor(9)",
"3^2",
"factor(10)",
"2*5",
"factor(100!)",
"2^97*3^48*5^24*7^16*11^9*13^7*17^5*19^5*23^4*29^3*31^3*37^2*41^2*43^2*47^2*53*59*61*67*71*73*79*83*89*97",
"factor(2*(2^30-35))",
"2*1073741789",
// x is the 10,000th prime
// Prime factors greater than x^2 are found using the Pollard rho method
"x=104729",
"",
"isprime(x^2+6)",
"1",
"isprime(x^2+60)",
"1",
"factor(2*(x^2+6))",
"2*10968163447",
"factor((x^2+6)^2)",
"10968163447*10968163447", // FIXME should be 10968163447^2
"factor((x^2+6)*(x^2+60))",
"10968163501*10968163447", // FIXME sort order
"x=quote(x)",
"",
};
void
test_factor_number(void)
{
test(__FILE__, s, sizeof s / sizeof (char *));
}