Random number generation quirk

[mpender]

I have had intermittent strange behavior when attempting to use the rand
function to create random numbers that I would like advice about. 

I usually use an expression like the following to produce random numbers
between 1 and 10 
digits = round (rand*10 + 0.5) 

This normally returns a number between 1 and 10.  But sometimes I get some
difficult to trace array index out of bound errors when I use the computed
value as an array index.  I suspect that sometimes the rand function returns
exactly 1.0 and then round (1.0 * 10 + 0.5) = 11 , which results in my index
out of bounds condition. 

I am familiar with a limitation of other implementations of the Mersenne
Twister that return a value between 0 (exclusive) and 1 (inclusive) -- does
anyone know if the Octave implementation works this way?  

If so, then I could replace rand with  (1 - rand) to get a value between 0
(inclusive) and 1 (exclusive) which would work fine for me.  Of course, it
won't do any good if the implementation can return both 0 (inclusive) and 1
(inclusive).  Otherwise, can anyone recommend a better way to generate
random numbers?  This is the way I have always seen it done before.

Thanks, Mike



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