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Calculation of pi by the Monte Carlo method
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main()
{
int i;
int n = 100000000;
int count = 0;
double x, y;
srand((unsigned)time(NULL));
double R = (double) RAND_MAX;
for (i = 0; i < n; i++) {
x = ((double) rand())/R;
y = ((double) rand())/R;
if (x*x + y*y <= 1) {
count++;
}
}
printf("%lf\n", 4.0*((double) count)/((double) n));
return 0;
}
#include <iostream>
#include <iomanip>
#include <random>
#include <chrono>
#include <stdlib.h>
double findpi(unsigned long n){
std::random_device seed_gen;
std::default_random_engine engine(seed_gen());
std::uniform_real_distribution<> dist(0.0, 1.0);
unsigned long count = 0;
/*
#pragma omp parallel for reduction(+:count)
*/
for(unsigned long i=0; i<n; i++){
double x = dist(engine);
double y = dist(engine);
if(x*x+y*y<=1){
count++;
}
}
return static_cast<double>(count)/n*4;
}
int main(int argc, char const* argv[]){
using namespace std::chrono;
unsigned long n;
if(argc>1){
n=strtoul(argv[1], nullptr, 10);
}else{
n=100000000;
}
auto start = steady_clock::now();
double pi = findpi(n);
auto end = steady_clock::now();
auto time = duration_cast<milliseconds>(end-start);
std::cout << "time = " << time.count() << "ms" << std::endl;
std::cout << std::setprecision(15) << pi << std::endl;
return 0;
}
#include <stdio.h>
#include <stdlib.h>
/*
dSFMT-src-2.2.3 package is downloaded from
http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/SFMT/index-jp.html
*/
#include "dSFMT-src-2.2.3/dSFMT.h"
#include "dSFMT-src-2.2.3/dSFMT.c"
int main(int ac, char *av[])
{
int n,i;
if (ac < 2) {
n = 100000000;
} else {
n = atoi(av[1]);
}
int count = 0;
double x, y;
dsfmt_t dsfmt;
dsfmt_init_gen_rand(&dsfmt, 12345);
const int BUF_SIZE = 0x10000;
double rs[BUF_SIZE];
for (i = 0; i < n; i++) {
if (i % BUF_SIZE == 0) {
dsfmt_fill_array_close1_open2(&dsfmt, rs, BUF_SIZE);
}
x = rs[(2*i ) % BUF_SIZE] - 1.0;
y = rs[(2*i+1) % BUF_SIZE] - 1.0;
if (x*x + y*y <= 1) {
count++;
}
}
printf("%lf\n", 4.0*((double) count)/((double) n));
return 0;
}
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main()
{
int i;
int n = 100000000;
int count = 0;
int x, y;
srand((unsigned)time(NULL));
int RR = RAND_MAX*RAND_MAX;
for (i = 0; i < n; i++) {
x = rand();
y = rand();
if (x*x + y*y <= RR) {
count++;
}
}
printf("%lf\n", 4.0*((double) count)/((double) n));
return 0;
}
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
/*
The following MT code is copy-and-pasted from
http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/MT2002/CODES/mt19937ar.c
*/
/* ----------------------------------------------------------- */
/*
A C-program for MT19937, with initialization improved 2002/1/26.
Coded by Takuji Nishimura and Makoto Matsumoto.
Before using, initialize the state by using init_genrand(seed)
or init_by_array(init_key, key_length).
Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. The names of its contributors may not be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Any feedback is very welcome.
http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
*/
//#include <stdio.h>
/* Period parameters */
#define N 624
#define M 397
#define MATRIX_A 0x9908b0dfUL /* constant vector a */
#define UPPER_MASK 0x80000000UL /* most significant w-r bits */
#define LOWER_MASK 0x7fffffffUL /* least significant r bits */
static unsigned long mt[N]; /* the array for the state vector */
static int mti=N+1; /* mti==N+1 means mt[N] is not initialized */
/* initializes mt[N] with a seed */
void init_genrand(unsigned long s)
{
mt[0]= s & 0xffffffffUL;
for (mti=1; mti<N; mti++) {
mt[mti] =
(1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti);
/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
/* In the previous versions, MSBs of the seed affect */
/* only MSBs of the array mt[]. */
/* 2002/01/09 modified by Makoto Matsumoto */
mt[mti] &= 0xffffffffUL;
/* for >32 bit machines */
}
}
/* initialize by an array with array-length */
/* init_key is the array for initializing keys */
/* key_length is its length */
/* slight change for C++, 2004/2/26 */
void init_by_array(unsigned long init_key[], int key_length)
{
int i, j, k;
init_genrand(19650218UL);
i=1; j=0;
k = (N>key_length ? N : key_length);
for (; k; k--) {
mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL))
+ init_key[j] + j; /* non linear */
mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
i++; j++;
if (i>=N) { mt[0] = mt[N-1]; i=1; }
if (j>=key_length) j=0;
}
for (k=N-1; k; k--) {
mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL))
- i; /* non linear */
mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
i++;
if (i>=N) { mt[0] = mt[N-1]; i=1; }
}
mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */
}
/* generates a random number on [0,0xffffffff]-interval */
unsigned long genrand_int32(void)
{
unsigned long y;
static unsigned long mag01[2]={0x0UL, MATRIX_A};
/* mag01[x] = x * MATRIX_A for x=0,1 */
if (mti >= N) { /* generate N words at one time */
int kk;
if (mti == N+1) /* if init_genrand() has not been called, */
init_genrand(5489UL); /* a default initial seed is used */
for (kk=0;kk<N-M;kk++) {
y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
}
for (;kk<N-1;kk++) {
y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
}
y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
mti = 0;
}
y = mt[mti++];
/* Tempering */
y ^= (y >> 11);
y ^= (y << 7) & 0x9d2c5680UL;
y ^= (y << 15) & 0xefc60000UL;
y ^= (y >> 18);
return y;
}
/* generates a random number on [0,0x7fffffff]-interval */
long genrand_int31(void)
{
return (long)(genrand_int32()>>1);
}
/* generates a random number on [0,1]-real-interval */
double genrand_real1(void)
{
return genrand_int32()*(1.0/4294967295.0);
/* divided by 2^32-1 */
}
/* generates a random number on [0,1)-real-interval */
double genrand_real2(void)
{
return genrand_int32()*(1.0/4294967296.0);
/* divided by 2^32 */
}
/* generates a random number on (0,1)-real-interval */
double genrand_real3(void)
{
return (((double)genrand_int32()) + 0.5)*(1.0/4294967296.0);
/* divided by 2^32 */
}
/* generates a random number on [0,1) with 53-bit resolution*/
double genrand_res53(void)
{
unsigned long a=genrand_int32()>>5, b=genrand_int32()>>6;
return(a*67108864.0+b)*(1.0/9007199254740992.0);
}
/* These real versions are due to Isaku Wada, 2002/01/09 added */
/* ----------------------------------------------------------- */
int main()
{
int i;
int n = 100000000;
int count = 0;
double x, y;
init_genrand(time(NULL));
for (i = 0; i < n; i++) {
x = genrand_real1();
y = genrand_real1();
if (x*x + y*y <= 1.0) {
count++;
}
}
printf("%lf\n", 4.0*((double) count)/((double) n));
return 0;
}
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
/*
The following MT code is copy-and-pasted from
http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/MT2002/CODES/mt19937ar.c
*/
/* ----------------------------------------------------------- */
/*
A C-program for MT19937, with initialization improved 2002/1/26.
Coded by Takuji Nishimura and Makoto Matsumoto.
Before using, initialize the state by using init_genrand(seed)
or init_by_array(init_key, key_length).
Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. The names of its contributors may not be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Any feedback is very welcome.
http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
*/
//#include <stdio.h>
/* Period parameters */
#define N 624
#define M 397
#define MATRIX_A 0x9908b0dfUL /* constant vector a */
#define UPPER_MASK 0x80000000UL /* most significant w-r bits */
#define LOWER_MASK 0x7fffffffUL /* least significant r bits */
static unsigned long mt[N]; /* the array for the state vector */
static int mti=N+1; /* mti==N+1 means mt[N] is not initialized */
/* initializes mt[N] with a seed */
void init_genrand(unsigned long s)
{
mt[0]= s & 0xffffffffUL;
for (mti=1; mti<N; mti++) {
mt[mti] =
(1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti);
/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
/* In the previous versions, MSBs of the seed affect */
/* only MSBs of the array mt[]. */
/* 2002/01/09 modified by Makoto Matsumoto */
mt[mti] &= 0xffffffffUL;
/* for >32 bit machines */
}
}
/* initialize by an array with array-length */
/* init_key is the array for initializing keys */
/* key_length is its length */
/* slight change for C++, 2004/2/26 */
void init_by_array(unsigned long init_key[], int key_length)
{
int i, j, k;
init_genrand(19650218UL);
i=1; j=0;
k = (N>key_length ? N : key_length);
for (; k; k--) {
mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL))
+ init_key[j] + j; /* non linear */
mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
i++; j++;
if (i>=N) { mt[0] = mt[N-1]; i=1; }
if (j>=key_length) j=0;
}
for (k=N-1; k; k--) {
mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL))
- i; /* non linear */
mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
i++;
if (i>=N) { mt[0] = mt[N-1]; i=1; }
}
mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */
}
/* generates a random number on [0,0xffffffff]-interval */
unsigned long genrand_int32(void)
{
unsigned long y;
static unsigned long mag01[2]={0x0UL, MATRIX_A};
/* mag01[x] = x * MATRIX_A for x=0,1 */
if (mti >= N) { /* generate N words at one time */
int kk;
if (mti == N+1) /* if init_genrand() has not been called, */
init_genrand(5489UL); /* a default initial seed is used */
for (kk=0;kk<N-M;kk++) {
y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
}
for (;kk<N-1;kk++) {
y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
}
y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
mti = 0;
}
y = mt[mti++];
/* Tempering */
y ^= (y >> 11);
y ^= (y << 7) & 0x9d2c5680UL;
y ^= (y << 15) & 0xefc60000UL;
y ^= (y >> 18);
return y;
}
/* generates a random number on [0,0x7fffffff]-interval */
long genrand_int31(void)
{
return (long)(genrand_int32()>>1);
}
/* generates a random number on [0,1]-real-interval */
double genrand_real1(void)
{
return genrand_int32()*(1.0/4294967295.0);
/* divided by 2^32-1 */
}
/* generates a random number on [0,1)-real-interval */
double genrand_real2(void)
{
return genrand_int32()*(1.0/4294967296.0);
/* divided by 2^32 */
}
/* generates a random number on (0,1)-real-interval */
double genrand_real3(void)
{
return (((double)genrand_int32()) + 0.5)*(1.0/4294967296.0);
/* divided by 2^32 */
}
/* generates a random number on [0,1) with 53-bit resolution*/
double genrand_res53(void)
{
unsigned long a=genrand_int32()>>5, b=genrand_int32()>>6;
return(a*67108864.0+b)*(1.0/9007199254740992.0);
}
/* These real versions are due to Isaku Wada, 2002/01/09 added */
/* ----------------------------------------------------------- */
int main()
{
int i;
int n = 100000000;
int count = 0;
double x, y;
init_genrand(time(NULL));
for (i = 0; i < n/100; i++) {
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
x = genrand_real1(); y = genrand_real1(); if (x*x + y*y <= 1.0) count++;
}
printf("%lf\n", 4.0*((double) count)/((double) n));
return 0;
}
#include <iostream>
#include <iomanip>
#include <random>
#include <chrono>
#include <stdlib.h>
double findpi(unsigned long n){
std::random_device seed_gen;
std::default_random_engine engine(seed_gen());
std::uniform_real_distribution<> dist(0.0, 1.0);
unsigned long count = 0;
#pragma omp parallel for reduction(+:count)
for(unsigned long i=0; i<n; i++){
double x = dist(engine);
double y = dist(engine);
if(x*x+y*y<=1){
count++;
}
}
return static_cast<double>(count)/n*4;
}
int main(int argc, char const* argv[]){
using namespace std::chrono;
unsigned long n;
if(argc>1){
n=strtoul(argv[1], nullptr, 10);
}else{
n=100000000;
}
auto start = steady_clock::now();
double pi = findpi(n);
auto end = steady_clock::now();
auto time = duration_cast<milliseconds>(end-start);
std::cout << "time = " << time.count() << "ms" << std::endl;
std::cout << std::setprecision(15) << pi << std::endl;
return 0;
}
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main()
{
int i;
int n = 100000000;
int count = 0;
double x, y;
srand((unsigned)time(NULL));
double R = (double) RAND_MAX;
for (i = 0; i < n; i++) {
x = ((double) rand())/R;
y = ((double) rand())/R;
if (x*x + y*y <= 1) {
count++;
}
}
printf("%lf\n", 4.0*((double) count)/((double) n));
return 0;
}
#include <stdio.h>
#include <stdlib.h>
/*
dSFMT-src-2.2.3 package is downloaded from
http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/SFMT/index-jp.html
*/
#include "dSFMT-src-2.2.3/dSFMT.h"
#include "dSFMT-src-2.2.3/dSFMT.c"
int main(int ac, char *av[])
{
int n,i;
if (ac < 2) {
n = 100000000;
} else {
n = atoi(av[1]);
}
int count = 0;
double x, y;
dsfmt_t dsfmt;
dsfmt_init_gen_rand(&dsfmt, 12345);
const int BUF_SIZE = 0x10000;
double rs[BUF_SIZE];
for (i = 0; i < n; i++) {
if (i % BUF_SIZE == 0) {
dsfmt_fill_array_close1_open2(&dsfmt, rs, BUF_SIZE);
}
x = rs[(2*i ) % BUF_SIZE] - 1.0;
y = rs[(2*i+1) % BUF_SIZE] - 1.0;
if (x*x + y*y <= 1) {
count++;
}
}
printf("%lf\n", 4.0*((double) count)/((double) n));
return 0;
}
#include <iostream>
#include <iomanip>
#include <random>
#include <chrono>
#include <stdlib.h>
double findpi(unsigned long n){
std::random_device seed_gen;
std::default_random_engine engine(seed_gen());
std::uniform_real_distribution<> dist(0.0, 1.0);
unsigned long count = 0;
/*
#pragma omp parallel for reduction(+:count)
*/
for(unsigned long i=0; i<n; i++){
double x = dist(engine);
double y = dist(engine);
if(x*x+y*y<=1){
count++;
}
}
return static_cast<double>(count)/n*4;
}
int main(int argc, char const* argv[]){
using namespace std::chrono;
unsigned long n;
if(argc>1){
n=strtoul(argv[1], nullptr, 10);
}else{
n=100000000;
}
auto start = steady_clock::now();
double pi = findpi(n);
auto end = steady_clock::now();
auto time = duration_cast<milliseconds>(end-start);
std::cout << "time = " << time.count() << "ms" << std::endl;
std::cout << std::setprecision(15) << pi << std::endl;
return 0;
}
#!/usr/bin/sh
echo "---------- findpi"
time ./findpi; echo ""
time ./findpi; echo ""
time ./findpi; echo ""
echo "---------- findpi_mt"
time ./findpi_mt; echo ""
time ./findpi_mt; echo ""
time ./findpi_mt; echo ""
echo "---------- findpi_dSFMT"
time ./findpi_dSFMT; echo ""
time ./findpi_dSFMT; echo ""
time ./findpi_dSFMT; echo ""
build: findpi findpi_int findpi_mt findpi_mt2 findpi_mtint findpi_g++ findpi_g++pragma findpi_dSFMT
findpi: findpi.c Makefile
gcc -Wall -O2 findpi.c -o findpi
findpi_int: findpi_int.c Makefile
gcc -Wall -O2 findpi_int.c -o findpi_int
findpi_mt: findpi_mt.c Makefile
gcc -Wall -O2 findpi_mt.c -o findpi_mt
findpi_mt2: findpi_mt2.c Makefile
gcc -Wall -O2 findpi_mt2.c -o findpi_mt2
findpi_g++: findpi.cc Makefile
g++ -Wall -Wextra -std=c++11 "-O3" "-march=native" "-fopenmp" findpi.cc -o findpi_g++
findpi_g++pragma: findpi.cc Makefile
g++ -Wall -Wextra -std=c++11 "-O3" "-march=native" "-fopenmp" findpi_pragma.cc -o findpi_g++pragma
findpi_dSFMT: findpi_dSFMT.c Makefile
gcc -O3 -DDSFMT_MEXP=521 findpi_dSFMT.c -o findpi_dSFMT
#!/usr/bin/sh
echo "---------- findpi"
time ./findpi; echo ""
time ./findpi; echo ""
time ./findpi; echo ""
echo "---------- findpi_mt"
time ./findpi_mt; echo ""
time ./findpi_mt; echo ""
time ./findpi_mt; echo ""
echo "---------- findpi_dSFMT"
time ./findpi_dSFMT; echo ""
time ./findpi_dSFMT; echo ""
time ./findpi_dSFMT; echo ""
---------- findpi
3.141763
real 0m2.602s
user 0m0.000s
sys 0m0.000s
3.141390
real 0m2.545s
user 0m0.000s
sys 0m0.000s
3.141491
real 0m2.584s
user 0m0.000s
sys 0m0.000s
---------- findpi_mt
3.141046
real 0m0.856s
user 0m0.000s
sys 0m0.016s
3.141617
real 0m0.865s
user 0m0.000s
sys 0m0.015s
3.141617
real 0m0.859s
user 0m0.000s
sys 0m0.000s
---------- findpi_dSFMT
3.141407
real 0m0.437s
user 0m0.000s
sys 0m0.000s
3.141407
real 0m0.449s
user 0m0.000s
sys 0m0.000s
3.141407
real 0m0.448s
user 0m0.000s
sys 0m0.015s
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