Random number between 1 and N

Intel_C_Intel — Tue, 14 Aug 2001 08:28:39 GMT

Thank you very much for your replies. Indeed, my question is how to generate a set of random numbers, say m random numbers, between 1 and N. Here m and N are integers and m <= N. Also, when the program is excuted each time, these m random numbers should be different.

Re: Random number between 1 and N

Steven_L_Intel1 — Tue, 14 Aug 2001 08:41:35 GMT

When you say "m <= N", that implies to me that you don't want any duplicates in the set. (If so, then they're not really random.) You can do this, but the technique differs.

Given a value R from RANDOM_NUMBER, you get an integer between 1 and N by doing

 INT(R * REAL(N)) + 1

If you want no duplicates, then you have to allocate an array of size N in which you record whether or not you've already seen each value. If you have, try again. There are various optimizations you can do on top of this.

Steve

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Random number between 1 and N

Re: Random number between 1 and N