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## Nonlinear Equation Solve

**From**: |
Thomas D. Dean |

**Subject**: |
Nonlinear Equation Solve |

**Date**: |
Tue, 14 Feb 2012 12:22:22 -0800 |

**User-agent**: |
Mozilla/5.0 (X11; FreeBSD amd64; rv:9.0) Gecko/20120126 Thunderbird/9.0 |

I have a set of 15 nonlinear equations in 15 unknowns.

`The equations are large, 3000 characters per equation, maybe 100 terms
``and of the form a1*(x1*x2*...*x14) + b1*(x1*x2* + ... + *x13*x15) + ...
`
The equations were generated by NEC4 and Maple for modeling an antenna.

`The function eqnsetf is 55 lines, 144000 characters. The top of the
``function extracts the values of y into the proper values. eqnsetf(y)
``returns a reasonable looking vector.
`
I tried
> size(y)
1 15
> [x, fval, info] =
fsolve (@eqnsetf,y',optimset("TolX",1e-20,"TolFun",1e-20));
> info
info = 0
If I reduce the tol's, fsolve does not reach a solution.
> [x, fval, info] =
fminunc (@eqnsetf,y',
optimset("TolX",1e18,"TolFun",1e18,"ComplexEqn","on"));

`error: __doglegm__: operator \: nonconformant arguments (op1 is 15x15,
``op2 is 225x1)
`error: called from:

`error: /usr/local/share/octave/3.4.3/m/optimization/fminunc.m at line
``386, column 3
``error: /usr/local/share/octave/3.4.3/m/optimization/fminunc.m at line
``233, column 9
`
Any ideas?
Tom Dean

**Nonlinear Equation Solve**,
*Thomas D. Dean* **<=**
*Message not available*
**Re: Nonlinear Equation Solve**, *Thomas D. Dean*, `2012/02/14`
**Re: Nonlinear Equation Solve**, *Ben Abbott*, `2012/02/14`
**Re: Nonlinear Equation Solve**, *Thomas D. Dean*, `2012/02/14`
**Re: Nonlinear Equation Solve**, *Dmitri A. Sergatskov*, `2012/02/14`
**Re: Nonlinear Equation Solve**, *Thomas D. Dean*, `2012/02/14`
**Re: Nonlinear Equation Solve**, *Olaf Till*, `2012/02/15`
**Re: Nonlinear Equation Solve**, *Olaf Till*, `2012/02/15`