how solve nonlinear equations with unknown constant?

[behzad1]

Hello,

I have a nonlinear equations system, that it seems cant solve with equations nnlinear solver. can u help me?

my equation is : H = a - b*Q^c

i have 3 pair of (H,Q) that get from user for input to program and are unknown in first step and user should be determine...

and equations wold be:

H1 = a - b*Q1^c

H2 = a - b*Q2^c

H3 = a - b*Q3^c

now, and after set H1,H2,H3,Q1,Q2,Q3 by user, we should solve this program for find a,b,c variables. have u any suggestion?

note: I have a pack of H,Q. it means that I must calculate a,b,c and repeat this act for finding a1,b1,c1 by new H,Q pairs, and then a2,b2,c2 ... untile user determind at first step.

Best Regards.

[Henrik_Volkers]

The LM nonlinear fit should be able to solve it, IF you have data that fit to the model! 

Nonlinear fitting depends a lot from a good guess of the starting values, BUT why not use the Power Fit VI (See help there) ??

Post your fitting code and some data to enable others to play with.