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Length: 799 (0x31f)
Types: TextFile
Notes: UNIX file
Names: »rpow.c«
└─⟦f27320a65⟧ Bits:30001972 Commodore 900 hard disk image with partial source code
└─⟦f4b8d8c84⟧ UNIX V7 Filesystem
└─ ⟦this⟧ »libmp/rpow.c«
#include "mprec.h"
/*
* Rpow sets the mint pointed to by "c" to the mint pointed to by "a"
* raised to the mint pointed to by "b" power. If "b" is negative then
* mperr is called with the appropriate error message.
* Note that no assumption is made as to the distinctness of "a", "b" and
* "c".
*/
void
rpow(a, b, c)
register mint *a, *b, *c;
{
mint al, bl;
int rem;
if (!ispos(b))
mperr("negative power");
/* make local copies of a and b */
minit(&al);
mcopy(a, &al);
minit(&bl);
mcopy(b, &bl);
/* form actual power */
sdiv(&bl, 2, &bl, &rem);
if (rem != 0)
mcopy(&al, c);
else
mcopy(mone, c);
while (!zerop(&bl)) {
mult(&al, &al, &al);
sdiv(&bl, 2, &bl, &rem);
if (rem != 0)
mult(c, &al, c);
}
/* clean up garbage */
mpfree(al.val);
mpfree(bl.val);
}