Row Echeleon Form/Forward elimination only

I am having trouble coding something that will just give me the matrix in row echelon form. I put asterisks around the line that isnt working and the error given is "Subscripted assignment dimension mismatch". I am not sure how to fix it. Below is also the PDF with a test case.

function [A_new, b_new] = forward_elimination(A, b)

%FORWARD_ELIMINATION - Performs forward elimination to put A into unit

% upper triangular form.

% A - original matrix of Ax = b

% b - original vector of Ax = b

% A_new - unit upper triangular A formed using Gaussian Elimination

% b_new - the vector b associated with the transformed A

% Default output

% A_new = A;

% b_new = b;

%********************************** TODO ********************************

% Perform Gaussian Elimination to evaluate turn A into a unit upper

% triangular matrix

[rowA,colA]=size(A);

[rowb,colb]=size(b);

if det(A)==0

    disp('Error')

    A_new=zeros(rowA,colA);

    b_new=zeros(rowb,colb);

elseif A==zeros(rowA,colA)

    disp('Error')

    A_new=zeros(rowA,colA);

    b_new=zeros(rowb,colb);

else

    sysarray=[A b];

    row1=sysarray(1,:);

    element1=A(1,1);

    rrow1=(row1/element1);

    array2=[rrow1;sysarray(2:end,:)];

    for i=1:(numel(b)-1)

        *array3(i)=array2(i+1,:)-array2(i,:).*array2(i+1,i+1);*

    end

    n_array2=array3;

    for j=1:(rowA-1)

        newArray=n_array2(j,:)/n_array2(j,j);

    end

    A_new=newArray(:,end-1);

    b_new=newArray(:,end);

end

end

Answer 1

[Aveek Podder]

Hi,

You are accessing the element of array3 by using linear indexing and you trying to fill it with a row vector. So you are getting a dimension mismatch error.

This issue can be solved by replacing the line within asterisks with the line given below.

    array3(i,:) = array2(i+1,:) - array2(i,:).*array2(i+1,i+1);