Sometjing to solve my problem

[Guest]

I need something an algorithm or something else to
help me with this function when a and b are given from functions before.
(1-(1/(1+r))^b)/r=a this is the function is there anything that can help me?
Is there any function that can search for the value of r when r 0<r<1? IF
somebody knows this it would be a great help for me if you display how i
should write the code in c++.

 

[Larry Brasfield]

I need something an algorithm or something else to
help me with this function when a and b are given from functions before.
(1-(1/(1+r))^b)/r=a this is the function is there anything that can help me?

With the application of some algebra, this will become a quadratic.
You can then use the well-known "quadratic formula" to solve for r.

Is there any function that can search for the value of r when r 0<r<1?

A search is not necessary. It can be solved analytically.

IF
somebody knows this it would be a great help for me if you display how i
should write the code in c++.

If this is homework, do it yourself. If you are unable to do simple
algebra or find a common formula on the web, and program for
a living, you have chosen the wrong career.

I suggest more care in choosing subject lines in the future. I and
some other people find it difficult to bother looking at a post when
the author cannot bother to do such a simple thing in order to save
readers' time.

 

[Larry Brasfield]

With the application of some algebra, this will become a quadratic.

Wrong. It is quadratic only for b==1.

You can then use the well-known "quadratic formula" to solve for r.


A search is not necessary. It can be solved analytically.

I would write a function to calculate the derivative w.r.t. r, then
use Newton's method (aka "Newton-Raphson method") to find
the roots of (1-(1/(1+r))^b)/r - a == 0. It should converge
rapidly over the range you gave for r.

 

[Rodrigo Corral [MVP]]

What about using the newton-raphson method...


--
Regards,
Rodrigo Corral González [MVP]

FAQ de microsoft.public.es.vc++
http://rcorral.mvps.org

 

[Rodrigo Corral [MVP]]

Or some other finding algorithm...

http://mathworld.wolfram.com/Root-FindingAlgorithm.html


--
Regards,
Rodrigo Corral González [MVP]

FAQ de microsoft.public.es.vc++
http://rcorral.mvps.org