diff options
Diffstat (limited to 'security/nss/lib/freebl/mpi/utils/pi.c')
| -rw-r--r-- | security/nss/lib/freebl/mpi/utils/pi.c | 171 |
1 files changed, 0 insertions, 171 deletions
diff --git a/security/nss/lib/freebl/mpi/utils/pi.c b/security/nss/lib/freebl/mpi/utils/pi.c deleted file mode 100644 index 7e3109786f..0000000000 --- a/security/nss/lib/freebl/mpi/utils/pi.c +++ /dev/null @@ -1,171 +0,0 @@ -/* - * pi.c - * - * Compute pi to an arbitrary number of digits. Uses Machin's formula, - * like everyone else on the planet: - * - * pi = 16 * arctan(1/5) - 4 * arctan(1/239) - * - * This is pretty effective for up to a few thousand digits, but it - * gets pretty slow after that. - * - * This Source Code Form is subject to the terms of the Mozilla Public - * License, v. 2.0. If a copy of the MPL was not distributed with this - * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ - -#include <stdio.h> -#include <stdlib.h> -#include <string.h> -#include <limits.h> -#include <time.h> - -#include "mpi.h" - -mp_err arctan(mp_digit mul, mp_digit x, mp_digit prec, mp_int *sum); - -int -main(int argc, char *argv[]) -{ - mp_err res; - mp_digit ndigits; - mp_int sum1, sum2; - clock_t start, stop; - int out = 0; - - /* Make the user specify precision on the command line */ - if (argc < 2) { - fprintf(stderr, "Usage: %s <num-digits>\n", argv[0]); - return 1; - } - - if ((ndigits = abs(atoi(argv[1]))) == 0) { - fprintf(stderr, "%s: you must request at least 1 digit\n", argv[0]); - return 1; - } - - start = clock(); - mp_init(&sum1); - mp_init(&sum2); - - /* sum1 = 16 * arctan(1/5) */ - if ((res = arctan(16, 5, ndigits, &sum1)) != MP_OKAY) { - fprintf(stderr, "%s: arctan: %s\n", argv[0], mp_strerror(res)); - out = 1; - goto CLEANUP; - } - - /* sum2 = 4 * arctan(1/239) */ - if ((res = arctan(4, 239, ndigits, &sum2)) != MP_OKAY) { - fprintf(stderr, "%s: arctan: %s\n", argv[0], mp_strerror(res)); - out = 1; - goto CLEANUP; - } - - /* pi = sum1 - sum2 */ - if ((res = mp_sub(&sum1, &sum2, &sum1)) != MP_OKAY) { - fprintf(stderr, "%s: mp_sub: %s\n", argv[0], mp_strerror(res)); - out = 1; - goto CLEANUP; - } - stop = clock(); - - /* Write the output in decimal */ - { - char *buf = malloc(mp_radix_size(&sum1, 10)); - - if (buf == NULL) { - fprintf(stderr, "%s: out of memory\n", argv[0]); - out = 1; - goto CLEANUP; - } - mp_todecimal(&sum1, buf); - printf("%s\n", buf); - free(buf); - } - - fprintf(stderr, "Computation took %.2f sec.\n", - (double)(stop - start) / CLOCKS_PER_SEC); - -CLEANUP: - mp_clear(&sum1); - mp_clear(&sum2); - - return out; -} - -/* Compute sum := mul * arctan(1/x), to 'prec' digits of precision */ -mp_err -arctan(mp_digit mul, mp_digit x, mp_digit prec, mp_int *sum) -{ - mp_int t, v; - mp_digit q = 1, rd; - mp_err res; - int sign = 1; - - prec += 3; /* push inaccuracies off the end */ - - mp_init(&t); - mp_set(&t, 10); - mp_init(&v); - if ((res = mp_expt_d(&t, prec, &t)) != MP_OKAY || /* get 10^prec */ - (res = mp_mul_d(&t, mul, &t)) != MP_OKAY || /* ... times mul */ - (res = mp_mul_d(&t, x, &t)) != MP_OKAY) /* ... times x */ - goto CLEANUP; - - /* - The extra multiplication by x in the above takes care of what - would otherwise have to be a special case for 1 / x^1 during the - first loop iteration. A little sneaky, but effective. - - We compute arctan(1/x) by the formula: - - 1 1 1 1 - - - ----- + ----- - ----- + ... - x 3 x^3 5 x^5 7 x^7 - - We multiply through by 'mul' beforehand, which gives us a couple - more iterations and more precision - */ - - x *= x; /* works as long as x < sqrt(RADIX), which it is here */ - - mp_zero(sum); - - do { - if ((res = mp_div_d(&t, x, &t, &rd)) != MP_OKAY) - goto CLEANUP; - - if (sign < 0 && rd != 0) - mp_add_d(&t, 1, &t); - - if ((res = mp_div_d(&t, q, &v, &rd)) != MP_OKAY) - goto CLEANUP; - - if (sign < 0 && rd != 0) - mp_add_d(&v, 1, &v); - - if (sign > 0) - res = mp_add(sum, &v, sum); - else - res = mp_sub(sum, &v, sum); - - if (res != MP_OKAY) - goto CLEANUP; - - sign *= -1; - q += 2; - - } while (mp_cmp_z(&t) != 0); - - /* Chop off inaccurate low-order digits */ - mp_div_d(sum, 1000, sum, NULL); - -CLEANUP: - mp_clear(&v); - mp_clear(&t); - - return res; -} - -/*------------------------------------------------------------------------*/ -/* HERE THERE BE DRAGONS */ |