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#include <stdio.h>
#include <stdlib.h>
#include <mpfr.h>
#include <math.h>
#include <stdbool.h>
#include <unistd.h>
#include <time.h>
// -lmpfr -lgmp -lm -Wall -Wextra -Werror
// Gauss-Legendre method
int calculate_pi(int len, bool infinite_mode, int delay_ms) {
mp_bitcnt_t precision = (mp_bitcnt_t)(len * 3.321928094 + 100); // Увеличил запас точности
mpfr_t a, b, t, p, a_next, t_tmp, p_tmp, pi;
mpfr_inits2(precision, a, b, t, p, a_next, t_tmp, p_tmp, pi, (mpfr_ptr)0);
mpfr_set_d(a, 1.0, MPFR_RNDN);
mpfr_sqrt_ui(b, 2, MPFR_RNDN); // b = sqrt(2)
mpfr_ui_div(b, 1, b, MPFR_RNDN); // b = 1/sqrt(2)
mpfr_set_d(t, 0.25, MPFR_RNDN);
mpfr_set_d(p, 1.0, MPFR_RNDN);
int iterations = (int)(log2(len)) + 3;
for (int i = 0; i < iterations; i++) {
// a_next = (a + b)/2
mpfr_add(a_next, a, b, MPFR_RNDN);
mpfr_div_2ui(a_next, a_next, 1, MPFR_RNDN);
// b = sqrt(a * b)
mpfr_mul(b, a, b, MPFR_RNDN);
mpfr_sqrt(b, b, MPFR_RNDN);
// t_tmp = t - p * (a - a_next)^2
mpfr_sub(t_tmp, a, a_next, MPFR_RNDN);
mpfr_sqr(t_tmp, t_tmp, MPFR_RNDN);
mpfr_mul(t_tmp, p, t_tmp, MPFR_RNDN);
mpfr_sub(t, t, t_tmp, MPFR_RNDN);
// p = 2 * p
mpfr_mul_2ui(p, p, 1, MPFR_RNDN);
// a = a_next
mpfr_set(a, a_next, MPFR_RNDN);
}
// π = (a + b)^2 / (4 * t)
mpfr_add(pi, a, b, MPFR_RNDN);
mpfr_sqr(pi, pi, MPFR_RNDN);
mpfr_mul_ui(t, t, 4, MPFR_RNDN);
mpfr_div(pi, pi, t, MPFR_RNDN);
if (!infinite_mode) {
printf("π = ");
mpfr_out_str(stdout, 10, len, pi, MPFR_RNDN);
printf("\n");
} else {
mpfr_exp_t exp;
char *pi_str;
pi_str = mpfr_get_str(NULL, &exp, 10, 0, pi, MPFR_RNDN);
if (pi_str == NULL) {
fprintf(stderr, "Error occurred while translating pi to char\n");
mpfr_clears(a, b, t, p, a_next, t_tmp, p_tmp, pi, (mpfr_ptr)0);
return 1;
}
if (exp == 1) {
printf("π = %c", pi_str[0]);
fflush(stdout);
if (delay_ms > 0) {
struct timespec ts;
ts.tv_sec = delay_ms / 1000;
ts.tv_nsec = (delay_ms % 1000) * 1000000L;
nanosleep(&ts, NULL);
}
printf(".");
fflush(stdout);
if (delay_ms > 0) {
struct timespec ts;
ts.tv_sec = delay_ms / 1000;
ts.tv_nsec = (delay_ms % 1000) * 1000000L;
nanosleep(&ts, NULL);
}
for (int i = 1; pi_str[i] != '\0'; i++) {
printf("%c", pi_str[i]);
fflush(stdout);
if (delay_ms > 0) {
struct timespec ts;
ts.tv_sec = delay_ms / 1000;
ts.tv_nsec = (delay_ms % 1000) * 1000000L;
nanosleep(&ts, NULL);
}
}
printf("\n");
} else {
printf("π = 0.%se%ld\n", pi_str, (long)exp);
}
mpfr_free_str(pi_str);
}
mpfr_clears(a, b, t, p, a_next, t_tmp, p_tmp, pi, (mpfr_ptr)0);
return 0;
}
int main(int argc, char *argv[]) {
int delay_ms = 500;
int count = 0;
bool infinite_mode = false;
bool help = false;
int opt;
while ((opt = getopt(argc, argv, "ihc:t:")) != -1) {
switch (opt) {
case 'i':
infinite_mode = true;
break;
case 'h':
help = true;
break;
case 'c':
count = atoi(optarg);
if(count <= 0) {
fprintf(stderr, "Invalid value for -c. Must be a positive integer.\n");
return 1;
}
break;
case 't':
delay_ms = atoi(optarg);
if(delay_ms < 0) {
fprintf(stderr, "Invalid value for -t. Must be a non-negative integer.\n");
return 1;
}
break;
case '?':
if (optopt == 'c' || optopt == 't') {
fprintf(stderr, "Option -%c requires an argument.\n", optopt);
} else {
fprintf(stderr, "Unknown option: -%c\n", optopt);
}
return 1;
default:
abort();
}
}
if (help) {
printf("tpi - C-written, MPFR-based CLI program for calculating π\n");
printf("ARGS:\n");
printf(" -h - Showing this message.\n");
printf(" -i - Infinitely outputs the digits of pi one at a time.\n");
printf(" -c=int - Outputs the number of digits of pi passed to the argument.\n");
printf(" -t=int - Setting the output speed in -i mode (milliseconds). The default value is 500.\n");
return 0;
}
if (infinite_mode) {
int internal_precision = 1000000;
if(count > 0 && count < internal_precision) {
internal_precision = count;
}
calculate_pi(internal_precision, true, delay_ms);
} else if (count > 0) {
calculate_pi(count, false, 0);
} else {
calculate_pi(500, false, 0);
}
return 0;
}
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