There is an error in my code

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Tianlan Yang 2021-3-18

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/777022-there-is-an-error-in-my-code

评论： Cris LaPierre 2021-3-18

Here is the function:

function [L,U] = eluinv(A)

[~,n]=size(A);

[L,U] = lu(A)

LU = roundingfixer(L*U);

if (A == LU)

disp('LU factorization is valid')

else

disp('A mistake was made somewhere.')

end

if (rank(U) == rank(A))

disp('U is an echelon form of A')

else

disp('A mistake was made somewhere.')

end

if (rank(A) == n)

% Use rref to row reduce the matrices

invL = [L eye(n)];

invU = [U eye(n)];

invL = rref(invL);

invU = rref(invU);

% Cut off the first half of the matrix

invL = invL(:,(n+1:n*2));

invU = invU(:,(n+1:n*2));

invA = roundingfixer(invU * invL)

P = roundingfixer(inv(A))

if (invA == P)

disp('LU works for calculating the inverse for A')

else

disp('Error in calculating the inverse for A')

end

else

sprintf('A is not invertible.')

invA = [];

end

roundingfixer.m:

function B = roundingfixer(A)

[m,n]=size(A);

A=closetozeroroundoff(A,7)

for i=1:m

for j=1:n

A(i,j) = round(A(i,j),8);

end

B=A;

end

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回答（1 个）

Cris LaPierre 2021-3-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/777022-there-is-an-error-in-my-code#answer_651782

编辑：Cris LaPierre 2021-3-18

在 MATLAB Online 中打开

Look at line 17: invL = [L eye(n)];

You are concatenating L and eye(n) horizontally. The error message is again telling you what the problem is. See this documentation page for more.

A = [1; 2]
A = 2×1
     1
     2
B = [3 4 5]
B = 1×3
     3     4     5
C = [A B]
Error using horzcat
Dimensions of arrays being concatenated are not consistent.

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Tianlan Yang 2021-3-18

Hi, I mean that is there a function that can replace horizontal concatenation (can both applied to row not equivalent situation)? Thank you so much！

Cris LaPierre 2021-3-18

I am not aware of a function that will do this for you. I believe you will need to write your code in a way to either ensure the two matrices have the same number of rows.

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