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xsun |
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#include<stdlib.h> |
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#include<stdio.h> |
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#include<math.h> |
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#define MYSEED 1234567 |
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#define NTRIALS 100000000 |
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/* double calculation(int trials) */ |
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/* { */ |
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/* int i, innerCount; */ |
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/* // init the random number generator */ |
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/* innerCount=0; */ |
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/* for(i=0;i<trials;++i) */ |
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/* { */ |
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/* } */ |
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/* pi= */ |
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/* return pi; */ |
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/* } */ |
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int main(int argc, char* argv[]) |
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{ |
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int i,innerCount; |
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double rms, diff; |
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double x,y,rSqr,pi; |
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FILE *outFile; |
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outFile=fopen("pi","w"); |
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fprintf(outFile,"#%s\t\t%s\n","number of trial","RMS"); |
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srand48( MYSEED ); |
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innerCount = 0; |
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for(i=0;i<NTRIALS;i++){ |
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x=(2.0*drand48())-1.0; |
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y=(2.0*drand48())-1.0; |
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rSqr= x*x + y*y; |
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if(rSqr<=1.0) innerCount++; |
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if( (i%100) == 0 ){ |
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pi = 4.0*(double)innerCount / (double)i; |
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diff = pi - M_PI; |
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rms = sqrt( diff * diff ); |
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fprintf(outFile,"%d\t\t%lf\n",i,rms); |
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} |
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} |
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printf("\n"); |
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printf("average of pi=%lf\n",pi); |
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fclose(outFile); |
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return 1; |
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} |
