Re: Will you please help a non-mathematician?

*To*: mathgroup at smc.vnet.net*Subject*: [mg5606] Re: Will you please help a non-mathematician?*From*: pecora at zoltar.nrl.navy.mil (Lou Pecora)*Date*: Fri, 27 Dec 1996 23:43:38 -0500*Organization*: Naval Research Lab*Sender*: owner-wri-mathgroup at wolfram.com

In article <59vp4j$f82 at dragonfly.wolfram.com>, DONKROUS at HALCYON.COM (Don Krouse) wrote: > Please be gentle, I'm not a mathematician. > > Solving the below equation for all variables, except i, works > satisfactorily. Trying to solve for i produces the following result. > > in[1] Solve[0==PV+PMT*((1-(1+i)^-n)/i)+FV*(1+i)^-n,i] > > Solve::tdep: > The equations appear to involve transcendental functions of > the variables in an essentially non-algebraic way. > > out[1] Solve[0 == FV/(1 + i)^n + ((1 - (1 + i)^(-n))*PMT)/i + PV, i] > > Can someone tell me how to get Mathematica to solve for i? I think what MMA is telling you is that it _can't_ solve for i. A quick glance at your equation makes me think there is no algebraic solution. Typically, equations involving a variable _and_ exponentials of the variable are unsolvable. There are special case exceptions. You really need to find someone mathematical to look at your case and see if it can be done. Sorry, that wasn't much help. The alternative is to use numerical solutions. Lou Pecora code 6343 Naval Research Lab Washington DC 20375 USA == My views are not those of the U.S. Navy. == ------------------------------------------------------------ Check out the 4th Experimental Chaos Conference Home Page: http://natasha.umsl.edu/Exp_Chaos4/ ------------------------------------------------------------