fsolve help

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Vasile Radu
Vasile Radu 2012-2-21
I would like to use fsolve for two nonlinear equations. When I put explicit equations in a function (LBBnlenew2.m) it is ok. But I need to put each equation as a funtion itself (defined already, with the same variables). In this case the error is:
??? Undefined function or method 'norm' for input arguments of type 'sym'.
Error in ==> trustnleqn at 138 normgradinf = norm(grad,inf);
Error in ==> fsolve at 295 [x,FVAL,JACOB,EXITFLAG,OUTPUT,msg]=...
Error in ==> LBB_Instability_Load_M2_solver2 at 2 x=fsolve('LBBnlenew2',x0);
Please let me know how to avoid the error. Thanks Vasile

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Sean de Wolski
Sean de Wolski 2012-2-21
class(grad)
class(inf)
If either of those are symbolic, you cannot use fsolve() since it's a numeric solver. Look into solve() instead.
  2 个评论
Walter Roberson
Walter Roberson 2012-2-21
It might be practical in your situation to use matlabFunction() to convert the symbolic function in to a function handle of a MATLAB function.
Sean de Wolski
Sean de Wolski 2012-2-21
@Walter, good idea, that would make gradObj much easier to use.

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