P2 is restricted to something similar to P1.

P1 and P2 represent reference frequencies generated by two different crystal oscillators. For various design reasons, it would be best if P2 is "similar" to P1. P2 preferably should be an integer, but can be a rational number.

For example if P1 is 50 and P2 were 55, then this is realizable in the hardware.

But for certain values of F between 4000 and 8000, F mod P1 = 0 and F mod P2 will also get close to 0. I would like to be able to find a value of P2 that will keep F mod P2 > some constant C, (10 for example) whenever F mod P1 = 0.