Iterative solution to nonlinear equation?

[testingHotAir]

Hi all,

I"m trying to put together a VI that will solve an equation of the form:

A = B*x^b+C*x^c

for the variable x (all others are numbers).  Does Labview have a block that will do the iterative solution or do I need to make my own.  I'm using Labview 8.6 Pro.

Thanks 

[DSPGuy]

This is a polynomial, so you could use the "Polynomial Roots.vi".

-Jim

[DSPGuy]

Well, a polynomial if b and c are integers.  If b and/or c are real numbers then you will need a zero finder.  There are two available, named "Newton Raphson Zero Finder.vi" and "Ridders Zero Finder.vi".

-Jim

[testingHotAir]

Thanks Jim!

I'm trying to get the Newton Raphson solver going right now, but it keeps giving me a syntax error.  I'm feeding it a string that looks like:  

50.00=0.019231*(2*a)^0.15+675*(2*a)^0.5

I've built this string programatically.  Is there something I'm missing here?

[DSPGuy]

Newton Raphson is expecting something like "expression=0", but the =0 is implied.  Try this.

0.019231*(2*a)^0.15+675*(2*a)^0.5-50

-Jim

[testingHotAir]

Ah.  Now it's working.  Thanks again!