how row 10 is Working Specific "A(i,k+1:n) " ??

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Raya Arafat
Raya Arafat on 26 Oct 2020
Answered: Rohit Pappu on 29 Oct 2020
function [x,det] = gauss(A,b)
% Solves A*x = b by Gauss elimination and computes det(A).
% USAGE: [x,det] = gauss(A,b)
if size(b,2) > 1; b = b’; end % b must be column vector
n = length(b);
for k = 1:n-1 % elimination phase
for i= k+1:n
if A(i,k) ∼=0
lambda = A(i,k)/A(k,k);
A(i,k+1:n) = A(i,k+1:n) - lambda*A(k,k+1:n);
b(i)= b(i) - lambda*b(k);
end
end
end
if nargout == 2; det = prod(diag(A)); end
for k = n:-1:1 % back substitution phase
b(k) = (b(k) - A(k,k+1:n)*b(k+1:n))/A(k,k);
end; x = b;

Answers (1)

Rohit Pappu
Rohit Pappu on 29 Oct 2020
Line no. 10 states that Update the (i)th row, (k+1)th to (n)th columns of A as follows
  • Multiply Lambda with the elements present in (k)th row, (k+1)th to (n)th columns of A to obtain a vector of dimensions (1, n-k)
  • Subtract the above resultant vector from the elements present in (i)th row, (k+1)th to (n)th columns of A to obtain a vector of dimensions (1, n-k)
  • Save the above resultant vector in (i)th row, (k+1)th to (n)th columns of A

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