error in while loop

Question

Piyanut Nanta 2015-6-17

0
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https://ww2.mathworks.cn/matlabcentral/answers/224243-error-in-while-loop

编辑： Nicholas Sullivan 2015-6-19

Hi, I want to loop of Jacobi method but error in while loop. help me please

clear all
clc
n=input('Number of equations (n): ');
A=input('Enter the matrix A,2D Matrix: ');
b=input('Enter the matrix b,Column vector: ');
E=input('Permissible error: ');
x0=zeros(1,n);
x=x0;
k=0;
while
    k=k+1;
    fprintf('%d',k);
    for i=1:n
        j=1:n
        if i~=j
            sum=sum+A(i,j)*x(j);
        end
        x(i)=(b(i)-sum)/A(i,i);
        fprintf('%10.5f',x(i));
    end
end

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Answer 1

Nicholas Sullivan 2015-6-17

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https://ww2.mathworks.cn/matlabcentral/answers/224243-error-in-while-loop#answer_182995

编辑：Nicholas Sullivan 2015-6-19

在 MATLAB Online 中打开

I think you might be missing a nested 'for' statement. Instead of

for i=1:n
  j=1:n

Write

for i=1:n
  for j=1:n

and then add an extra 'end' statement where appropriate.

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Walter Roberson 2015-6-18

在 MATLAB Online 中打开

k will never test equal to k+1 unless k is infinity.

The code was not "while k=k+1", it just looked like that because it was not formatted. Instead it had a 'while" with nothing else on the same line. That needs to be changed to something like

while true

That would create an infinite loop. Possibly along the way some test involving E (permissible error) is intended. The way to calculate the current error is not documented here, though, so no suggestions on that.

Nicholas Sullivan 2015-6-19