How do I choose variables for a PRNG?

How do I choose variables for a PRNG?
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I know that you can generate pseudorandom numbers using this formula:
X_{n + 1} = a * X_n mod c

As far as I understand, the first value in X (i. e., X_0) is the seed for the PRNG.

What I don’t understand is what a and c are. The tutorial I used also talks of a modulus (m, 0 < m) and tells me that a (0 < a < m) is a multiplier and c (0 < c <= m).
A simple google search does not reveal anything much about these variables.

Can someone please explain or give me a link to a good website where I can read about these parameters?


Nobody has answered this yet, so I’m going to BUMP.


Here’s a wiki about the formula and it’s parameters.

(and values that some languages use for their PRNG)


Thanks a lot! I’ll go through it.