Using solve and sigma from programming

[photometer]

Hello,
I have an equation

pv = cf/(1+r) + cf/(1+r)^1 + cf/(1+r)^2 + ... + cf/(1+r)^n

I have the value of pv, cf and I need to find the value of r. How do I call the CAS.solve() and pass a function that does summation?

BEGIN
LOCAL pv,cf,result;
pv:= 100;
cf:= 10;
result:=CAS.solve(.....); // <- how do I write this?


END;

[roadrunner]

I deleted my previous post because i had an error in the program.

I'm thinking this:

PHP Code:

EXPORT testsum()
BEGIN
 LOCAL pv,cf,result;
 pv:=100;
 cf:=10;
 result:=CAS(EVAL("solve("+pv+" = (sum("+cf+"/(1+r)^n,n,0,∞)),r)"));
 return result;
END; 


is what you are looking for?

-road

[photometer]

Thanks very much. It works now.