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%I need help in developing a function file GE_m(A,b) to determine the pivot row r

% such that a(rk) is the first nonzero entry among a(kk),a(k+1)...a(n,k).

% if a(kk)=a(k+1,k)=a(nk)=0 then pivot out that 'A is not invertible' and quit.

% this is the other function i will be calling in my comand window and this function is correct

%function x=ut_sys(U,c)

%n=length(U);

%x=zeros(n,1);

%x(n)=c(n)/U(n,n);

%for i=n-1:-1:1

% s=0;

% for j=n:-1:i+1

%s =s+U(i,j)*x(j);

% end

% x(i) = (c(i)-s) /U(i,i);

%end

%end

% i need help with the function below!! i cannot get it working

function [A,b]=GE_m(A,b)

n =length(b);

for k=1:n-1

ap=abs(A(k,k));

r=k;

while ap < (n)*e-15

r=r+1;

end

end

if ap , (n)*e-15

disp('A is not invertible');

end

end

Ayush Gupta
on 17 Sep 2020

The following problem can be solved by using nested for loop. Refer to the following code to see how to solve this:

function [A,b]=a1(A,b)

n =length(b);

flag = 0;

for k=1:n-1

for i = k:n-1

if(a(k,i) ~= 0)

flag = 1;

end

end

end

if(flag == 1)

disp('A is not invertible')

end

end

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