If statements

Hey Guys,

I have a model that predicts supply based on 3 factors 1) Month of year, 2) day of week and 3) time of day

Currently the model is set up so that from a table (g1) in the model if(a1=sunday,g1,if a1=monday,g2 etc) i have this formula set up for each hour of the day so it puuls supply based on that hour of the day given the day of the week.

The problem i am having is adding in the month of the year as the formulas get very very messy and very long. Is their an easier way to add in the month as oppose to using a general if statement (e.g. if(and(a1=january,a2=sunday,b3,if(and(a1=january,a2=monday,b4

This is what I have now and I have to that for 7 days a week 12 months a year and 24 hours a day. Thats over 2000 different combinations. Is there an easier way to create this that i may be missing.

thanks in advance