I am looking for the algorithm used to define the RATE() function in excel. I'd prefer it to be in ruby.
It needs to have the same params as the excel function: RATE( number_payments, payment, PV, FV, Type, Estimate ). FV, Type and Estimate seem to be optional as they take default values.
This doesn't seem to do the trick for me: http://www.experts-exchange.com/Software/Office_Productivity/Office_Suites/MS_Office/Q_20531809.html