Biorythms IIRC work on three 'cycles' of differing length. The ideology is that when all three are at a high you are at your most 'positive'
so mathematically, work out the time for 3 cycles to cover a full set to meet at zero, work out how many of these cycles a person has lived (remember leap years), the work out how far in you are. at this point you work on what part of a sine wave cycle you would be given the relevant frequencies of teh 3 cycles. Plot teh last 10 days or so to show how it is 'flowing'
See, Maths all teh way!!!
