Hi, I am trying to calculate a monthly payment for a loan in Ruby. Does anyone know what the equivalent for math.pow in Java is for Ruby? @monthlypayment = @principal*@rate/(1-Math.pow(1/(1+@rate),@payments)) Ive searched everywhere and cant seem to find anything. thanks Johnny B

on 2007-03-30 00:43

on 2007-03-30 01:02

On Fri, Mar 30, 2007 at 05:43:38AM +0900, John B. wrote: > I am trying to calculate a monthly payment for a loan in Ruby. Does > anyone know what the equivalent for math.pow in Java is for Ruby? > > @monthlypayment = @principal*@rate/(1-Math.pow(1/(1+@rate),@payments)) > > Ive searched everywhere and cant seem to find anything. http://www.rubycentral.com/book/ref_c_float.html#F... Look for 'exponentiation'

on 2007-03-30 01:07

On 3/30/07, John B. <removed_email_address@domain.invalid> wrote: > Does > anyone know what the equivalent for math.pow in Java is for Ruby? > > @monthlypayment = @principal*@rate/(1-Math.pow(1/(1+@rate),@payments)) > > Is this what you are looking for? p 4 ** 3 Harry -- http://www.kakueki.com/ruby/list.html Japanese Ruby List Subjects in English

on 2007-03-30 01:08

John B. wrote: > Hi, > > I am trying to calculate a monthly payment for a loan in Ruby. Does > anyone know what the equivalent for math.pow in Java is for Ruby? > > @monthlypayment = @principal*@rate/(1-Math.pow(1/(1+@rate),@payments)) > > Ive searched everywhere and cant seem to find anything. > > thanks > > Johnny B I think this is what you're looking for: irb(main):001:0> 2 ** 1 => 2 irb(main):002:0> 2 ** 2 => 4 irb(main):003:0> 2 ** 3 => 8 irb(main):004:0> 2 ** 4 => 16

on 2007-03-30 13:21

Drew O. wrote: > John B. wrote: >> Hi, >> >> I am trying to calculate a monthly payment for a loan in Ruby. Does >> anyone know what the equivalent for math.pow in Java is for Ruby? >> >> @monthlypayment = @principal*@rate/(1-Math.pow(1/(1+@rate),@payments)) >> >> Ive searched everywhere and cant seem to find anything. >> >> thanks >> >> Johnny B > > I think this is what you're looking for: > > irb(main):001:0> 2 ** 1 > => 2 > irb(main):002:0> 2 ** 2 > => 4 > irb(main):003:0> 2 ** 3 > => 8 > irb(main):004:0> 2 ** 4 > => 16 Yes this is what i am looking for. How do i then use it to calculate amonthly payment, i have tried quite a few things but cant get the syntax right: @monthlypayment = @principal*@rate/(1-**(1/(1+@rate),@payments)) So for the example below: Suppose you finance your car with a loan of $12000 at a yearly interest rate of 11% for four years, and make equal payments monthly. How much will your payments have to be? Here the parameters are principal P = $12000, interest rate i = 0.11, number of years n = 4, and number of periods per year q = 12. Then the monthly car payment M is given by M = Pi/[q(1-[1+(i/q)]-nq)], = ($12000)(0.11)/[(12)(1-[1+(0.11/12)]-(4)(12))], = $110/(1-1.009166666...-48), = $310.15. Anyone done this before?

on 2007-03-30 13:53

Alle venerdÃ¬ 30 marzo 2007, John B. ha scritto: > >> > > irb(main):003:0> 2 ** 3 > So for the example below: > = $310.15. > > > Anyone done this before? ** is an operator, just like + or *; it's used this way: base**exponent. In your case, you should write: @principal*@rate/(1-1/(1+@rate)**@payments) I hope this helps Stefano