Re: Controlling ('rand') random number upper limit

According to the documentation, rand returns a number from 0 to RAND_MAX,
and I'm not sure what RAND_MAX is defined as, most likely 32767, 65535,
or some other such number.  With rand it has always been necessary to
do some math calculations to return the number you want.

Some random number generators return a number from 0 to .999999.  The formula
then is: 
x = random_number * range + 1
which would return a number from 1 to 10.

I've found myself forcing the number that C's rand returns into the range
0 to .99999999 because I am familiar with that method, then doing my 
calculations.

random_number/32767 would return such a range if 32767 was RAND_MAX.

So the formula becomes:
x = (random_number/RAND_MAX) * range + 1

In other languages I've always stuck this into my own wrapper and just called
that.  Watch out for precision problems.

(Pseudo code:)
D RandomReturn          S         5  0

C               Eval    RandomReturn = (rand() / 32767) * Range + 1
C               Return  RandomReturn

HTH

Regards,

Jim Langston

Me transmitte sursum, Caledoni!

Paul Jackson wrote:
> 
> Is there a way to control the maximum number that the
> 'rand' c function returns to the RPG Program? For
> example I may only be interested in a value from 1 to
> 100.
> 
> Many thanks in advance,m
> 
> -Paul
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