Non-Uniform Random Number Generator Implementation

Question

I need a random number generator that picks numbers over a specified range with a programmable mean.

For example, I need to pick numbers between 2 and 14 and I need the average of the random numbers to be 5.

I use random number generators a lot. Usually I just need a uniform distribution.

I don't even know what to call this type of distribution.

Thank you for any assistance or insight you can provide.

Answer 1

My first idea would be:

• generate numbers in the range 0..1
• scale to the range -9..9 ( x-0.5; x*18)
• shift range by 5 -> -4 .. 14 (add 5)
• truncate the range to 2..14 (discard numbers < 2)

that should give you numbers in the range you want.

Answer 2

You need a distributed / weighted random number generator. Here's a reference to get you started.