solving two of nonlinear equations and two unknwons.
- From: Mike <SulfateIon@xxxxxxxxx>
- Date: Fri, 17 Oct 2008 00:38:38 -0700 (PDT)
Hi
I have a problem about solving two of nonlinear equations. And I only
have two unknown.
The function is run by some complex program and I think it's very hard
to solve it analytically.
Thus, I cannot have anallytic Jacobian.
I try numerically. I use IMSL and fortran.
First I use NEQBF(purpose:Solves a system of nonlinear equations using
factored secant update with a finite-difference approximation to the
Jacobian.). Then I find there is no constraint (reasonable bounds)
for this.
Does anybody know if there is constrainted nonlinear equations solver
for imsl?
Then I switch to use BCLSF(purpose:
Solves a nonlinear least squares problem subject to bounds on the
variables using a modified
Levenberg-Marquardt algorithm and a finite-difference Jacobian.)
It is quite sensitive to guess vectors. It traps to a wrong solution.
Since I have two unkown for two nonlinear equations. I doubt if I
need to use this (least squares).
Is there a better choice for IMSL fortran?
Mike
.
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