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我正在使用fminsearch通过扰动某些参数来最小化粗尺度协方差和细尺度协方差平均值之间的误差。这些是 2 行代码行，我在其中使用我打算扰乱的三个参数fminsearch调用目标函数：minimize_me

opts = optimset('display', 'iter');
[x,fval,exitflag] = fminsearch( @(x) minimize_me(x(1), x(2), x(3)), [2, 5, 90], opts);

该函数minimize_me如下所示，它在其体内使用了更多函数：

function diff = minimize_me(a_minor, a_major, theta)

%# Grid and model parameters
nModel=50;
nModel_want=1;
nI_grid1=5;
Nth=1;
nRow.Scale1=5;
nCol.Scale1=5;
nRow.Scale2=5^2;
nCol.Scale2=5^2;
nCell.Scale1=nRow.Scale1*nCol.Scale1;

%% Covariance computation, averaging and difference of coarse and fine scale averaged covariances

% Reading files by using the function 'general_gslib_file_to_mat.mat'
[Deff_matrix_NthModel,~,~]=general_gslib_file_to_mat(nModel,nCell.Scale1,nModel_want,nI_grid1,Nth,'effective_dispersivity_coarsegrid5x5_gslib_format');

%# Maximum value of covariance/variogram at coarse scale
sill = var(reshape(Deff_matrix_NthModel,nCell.Scale1,1)); % variance of the coarse data matrix of size (nRow.Scale1 X nCol.Scale1)

%% Compute the covariance at different lags using the function general_CovModel.m

for ihRow = 1:nRow.Scale1
    for ihCol = 1:nCol.Scale1
        [cov.Scale1(ihRow,ihCol),heff.Scale1(ihRow,ihCol)] = general_CovModel(theta, ihCol, ihRow, a_minor, a_major, sill, 'Exp');
    end
end

for ihRow = 1:nRow.Scale2
    for ihCol = 1:nCol.Scale2
        [cov.Scale2(ihRow,ihCol),heff.Scale2(ihRow,ihCol)] = general_CovModel(theta, ihCol/(nCol.Scale2/nCol.Scale1), ihRow/(nRow.Scale2/nRow.Scale1), a_minor, a_major,...
            sill/(nRow.Scale2*nCol.Scale2), 'Exp');
    end
end

%# Scale-up of fine scale values by averaging which is done using the function general_AverageProperty.m
[covAvg.Scale2,var_covAvg.Scale2,varNorm_covAvg.Scale2] = general_AverageProperty(nRow.Scale2/nRow.Scale1,nCol.Scale2/nCol.Scale1,1,nRow.Scale1,nCol.Scale1,1,cov.Scale2,1);

%# Difference between the coarse scaled covariance and average of fine scale covariance
diff = (covAvg.Scale2 - cov.Scale1)^2;
end

但是，在运行前面显示的前两行代码时，我收到此错误：

??? Subscripted assignment dimension mismatch.

Error in ==> fminsearch at 195
fv(:,1) = funfcn(x,varargin{:});

有人可以指出有什么问题吗？谢谢！

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1 回答 1

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问题是，您没有为任何人提供足够的资源来测试您的代码。

所以你应该...

  • 学习使用调试器！在任何情况下都是一个好主意。这将帮助您发现自己做错了什么，同时也教您使用有价值的工具。

  • 使用起始值测试您的函数一次。它返回什么？你试过这个吗？总是做这个测试。验证您的目标是否符合您的预期。

Fminsearch 需要一个标量输出来最小化。你的功能有吗？

哦，顺便说一句，定义一个名为 diff 的变量或任何作为 MATLAB 中已经存在的有用工具的变量是一个糟糕的主意。否则，您只是恳求在您的代码中创建难以发现的错误。

于 2012-11-18T16:33:54.600 回答