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Resolution of equation under constraints with 'fminbnd'

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studentU
studentU 2015-6-23
评论： Walter Roberson 2015-6-26
hi, i must resolve the system of equations with two variable x and y, and i use 'solve' to do it, but i must limit the solution between an interval, can fminbnd function replace 'solve' in this case
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studentU
studentU 2015-6-23
编辑：studentU 2015-6-23
thank's for ue repply, YES, i have tow equations with tow unknows, and my system can have multiple solutions.
Torsten
Torsten 2015-6-23
The reason why I ask is that it is usually not possible to restrict the solution to a certain interval.
The best you can expect is to get values for x and y such that
f1(x,y)^2+f2(x,y)^2
is minimized if you want to solve
f1(x,y)=0 and f2(x,y)=0.
If this is what you want you can proceed as Matt suggested.
Best wishes
Torsten.

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回答（1 个）

Matt J
Matt J 2015-6-23
No, fminbnd only handles problems in a single unknown. You can use lsqnonlin, if you have the Optimization Toolbox, or you can try things on the File Exchange, like fminsearchbnd
http://www.mathworks.com/matlabcentral/fileexchange/8277-fminsearchbnd--fminsearchcon
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studentU
studentU 2015-6-26
it become already error: Failure in initial user-supplied objective function evaluation. LSQNONLIN cannot continue.
Walter Roberson
Walter Roberson 2015-6-26
Your x0, your initial points, is -pi/2 which is a scalar. But your objective function expects a vector of length two (or more). You need to supply a vector of length 2 instead of -pi/2

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