Minimizing an equation to 0

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AAS 2022-9-11

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https://ww2.mathworks.cn/matlabcentral/answers/1802850-minimizing-an-equation-to-0

编辑： Bruno Luong 2022-9-11

I have an equation where I am trying to reduce the RMS to 0 i.e RMS(A-(B+C)<=0. A,B and C are known but the RMS is not equal to 0 . Now, I want to modify this equation such that RMS(A-(k1*B+k2*C)<=0. I want to find k1 and k2 to make the RMS as close to 0. How could I do this?

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Walter Roberson 2022-9-11

are A, B, C matrices? Are k1 and k2 scalar?

AAS 2022-9-11

yes, A,B and C are matrices and k1 and k2 are scalars.

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Answer 1

Alan Stevens 2022-9-11

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Try fminsearch

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AAS 2022-9-11

I tried to implement it this way.. however, it did not produce good resuts, barely did any minimization. Am I implementing it right?

f = @(k) rms(C-(k(1)*A+k(2)*B));;

k0=[1 1];

[xmin] = fminsearch(f,k0,options);

f(xmin);

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Answer 2

Torsten 2022-9-11

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https://ww2.mathworks.cn/matlabcentral/answers/1802850-minimizing-an-equation-to-0#answer_1051120

编辑：Torsten 2022-9-11

在 MATLAB Online 中打开

A = [4 3; 6 2; 7 -3];
B = [1 -3; 2 2; 5 -pi];
C = [12 -0.5; 7 -3; 0 1];
fun = @(p)reshape(A-(p(1)*B+p(2)*C),[],1);
sol = lsqnonlin(fun,[1 1])
Local minimum found.

Optimization completed because the size of the gradient is less than
the value of the optimality tolerance.
sol = 1×2
    0.9421    0.3061
error = rms(fun(sol))
error = 2.7826