Created
August 29, 2021 12:33
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Solution per tstanisl at https://stackoverflow.com/a/68959383/5660198
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| #include <stdio.h> | |
| #include <stdlib.h> | |
| #include <stdint.h> | |
| int compare (const void * a, const void * b) | |
| { | |
| if (*(double*)a > *(double*)b) return 1; | |
| else if (*(double*)a < *(double*)b) return -1; | |
| else return 0; | |
| } | |
| double grand_f_0_1(){ | |
| static FILE * fp = NULL; | |
| uint64_t bits; | |
| if(fp == NULL) fp = fopen("/dev/urandom", "r"); | |
| fread(&bits, sizeof(bits), 1, fp); | |
| return (double)bits * 5.421010862427522170037264004349e-020; // https://stackoverflow.com/a/26867455 | |
| } | |
| int main() | |
| { | |
| const int n = 10; | |
| double values[n]; | |
| double diffs[n]; | |
| double shift; | |
| int i, j; | |
| for(j=0; j<1000000; j++) { | |
| values[0] = 0.; // https://stackoverflow.com/a/68959383/5660198 | |
| for(i=1; i<n; i++) values[i] = grand_f_0_1(); | |
| qsort(values+1, n-1, sizeof(double), compare); | |
| shift = grand_f_0_1(); | |
| for(i=0; i<n; i++) { | |
| values[i] += shift; | |
| if(values[i] >= 1.) values[i] -= 1.; | |
| } | |
| // cannot resort here! | |
| for(i=0; i<n; i++) { | |
| diffs[i] = values[(i+1)%n] - values[i]; | |
| if(diffs[i] < 0.) diffs[i] += 1.; | |
| } | |
| for(i=0; i<n; i++) printf("%.5f%s", diffs[i], i<(n-1)?"\t":"\n"); | |
| } | |
| return(0); | |
| } |
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