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Message: [QUOTE="Frank Silvermann, post: 2468571"] [snipped away the other 95 percent] It was hard for me to determine what was relevant. Although I didn't use the SWAP macro for on the original post, I was glad to have it around to deal with the expected and unmathematical objection that they be reversed. #include <stdio.h> #include <stdlib.h> #include <time.h> #include <math.h> #define SWAP(m, n) (tmp = (m), (m) = (n), (n) = tmp) #define ITERATIONS 100 int rand_in_range(int, int); int main(void) { int tja, i , j, tmp, m, n; float mu; /* all declarations in main need to be north of here */ /* seed timer */ srand(time(NULL)); /* call rand */ j = 0; m = 40; n = 3; if (m > n) SWAP(m, n); printf("range is [%d, %d]\n", m, n); mu = (float)ITERATIONS *((float)m +(float)(m - n) /(float)2); printf("mu is %f\n", mu); for (i=0; i < ITERATIONS; i++) { tja = rand_in_range(m, n); if (i < 10) printf("return is %d\n", tja); j += tja; } printf("j is %d\n", j); return 0; } int rand_in_range(int m, int n) { /*seed srand in main */ /* [m, n] is range */ int t, top, diff, o, tmp; if (m == n) return m; if (m > n) SWAP(m, n); diff = n - m; top = RAND_MAX - (RAND_MAX % diff); /* control */ do t = rand(); while (t > top); o = t % (diff + 1) ; o = o + m; return o; } /* end source */ I think this is getting closer. The mu fiasco shows why it's sometimes hard to trim out of a function on the fly. If ITERATIONS is a positive power of ten, then the expected value is going to be the average of the two inputs with the decimal point moved. frank [/QUOTE]

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