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smileheaven

金虫 (小有名气)

[求助] MATLAB非线性优化拟合怎么改才正确

想对函数z求一下x和Fval的最优解,其中x1的取值范围在0.3到1.8,x2的取值范围在1到2,均为闭区间。以下是自己编的程序
    function [x fval history] = myproblem1(x0)
        history = []
        options = optimset('OutputFcn', @myoutput)
        [x fval] = fminsearch(@objfun, x0,options)
        function stop = myoutput(x,optimvalues,state)
            stop=[]
            if state == 'iter'
                history = [history; x]
            end
        end
        function z = objfun(x)
            z = 124.5993*x(1)^2-371.4544*x(1)+712.1124-1359.4398*x(2)^2+4028.7765*x(2)-2244.7098
        end
    end
但是返回的错误却是
??? In an assignment  A( = B, the number of elements in A and B
must be the same.

Error in ==> callAllOptimOutputFcns at 12
    stop(i) = feval(OutputFcn{i},xOutputfcn,optimValues,state,varargin{:});

Error in ==> fminsearch>callOutputAndPlotFcns at 478
            stop = callAllOptimOutputFcns(outputfcn,xOutputfcn,optimValues,state,varargin{:}) || stop;

Error in ==> fminsearch at 213
    [xOutputfcn, optimValues, stop] = callOutputAndPlotFcns(outputfcn,plotfcns,v(:,1),xOutputfcn,'init',itercount, ...

Error in ==> myproblem1 at 4
        [x fval history] = fminsearch(@objfun, x0,options)
请各位虫哥虫姐帮忙看看,谢谢啦
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smileheaven

金虫 (小有名气)

引用回帖:
2楼: Originally posted by csgt0 at 2012-05-25 13:35:05
stop=false;


结果
state =

done


Exiting: Maximum number of function evaluations has been exceeded
         - increase MaxFunEvals option.
         Current function value: -319813720581 ...

那为什么我这边计算不出来呢?什么地方错了,如果可能,还请您指教,谢谢
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3楼2012-05-25 14:01:02
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csgt0

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彩色挂图

【答案】应助回帖

★ ★ ★ ★ ★
感谢参与,应助指数 +1
smileheaven: 金币+5, ★★★★★最佳答案, 谢谢 2012-06-11 12:18:10
stop=false;


结果
state =

done


Exiting: Maximum number of function evaluations has been exceeded
         - increase MaxFunEvals option.
         Current function value: -31981372058113011000000000000000000000000000000000000000000000000000000000000000000000000000.000000


x =

  1.0e+044 *

    0.1905    1.5349


fval =

-3.1981e+091


result =

  1.0e+044 *

    0.1905    1.5349
showmethemoney
2楼2012-05-25 13:35:05
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csgt0

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【答案】应助回帖

stop只能是false或true,然后通过stop来判断是否跳出。你不用它就设为false,而不是[];再用state判断

Stop Flag

The output argument stop is a flag that is true or false. The flag tells the optimization function whether the optimization should quit or continue. The following examples show typical ways to use the stop flag.
Stopping an Optimization Based on Data in optimValues

The output function can stop an optimization at any iteration based on the current data in optimValues. For example, the following code sets stop to true if the objective function value is less than 5:

function stop = myoutput(x, optimValues, state)
stop = false;
% Check if objective function is less than 5.
if optimValues.fval < 5
    stop = true;
end

Stopping an Optimization Based on GUI Input

If you design a GUI to perform optimizations, you can make the output function stop an optimization when a user clicks a Stop button on the GUI. The following code shows how to do this, assuming that the Stop button callback stores the value true in the optimstop field of a handles structure called hObject stored in appdata.

function stop = myoutput(x, optimValues, state)
stop = false;
% Check if user has requested to stop the optimization.
stop = getappdata(hObject,'optimstop');
showmethemoney
4楼2012-05-25 14:25:43
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