[wanabidii] Re: How to use MATLAB to analyse wastewater treatment systems by Gauss elimination?

Nawashukuru wote mliojitokeza kunisaidia.

 

Kwa faida ya wengine; kosa nililofanya ni kuingiza seti bila kuweka ";" i.e. b = [0 0 0 0 0 0 0 0 0 0 1000] "1 row, 11 columns". Kwakua seti yangu "a" ni ya 11x11 ndiyo maana mahesabu yaligoma.

 

Nilipoweka seti b = [0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 1000],nilipata "11 rows, 1 column". Mahesabu yalikubali kwenye MATILAB japo majibu yalikuwa "NAN".

 

Niliporekebisha namba kwenye seti "a" kulingana na hitaji langu, mahesabu yalikubali.

 

Asanteni sana.

On Thu, Oct 3, 2013 at 9:26 PM, Mwema Felix <mwema.felix@gmail.com> wrote:

Dear colleagues

 

I tried to use MATLAB to solve a numerical method problem on waste water treatment system analysis (membrane reactor) by "Gauss elimination" with the below m-file.

 

Unfortunately, I received an error message as below:-

 

Error in ==> Gauss at 10
ab = [a,b];

 

The matrix I am working on is 11 x 11, its determinant is zero.

 

Matrix

 

a = [1 0 -1 0 -1 0 0 0 0 0 0; 0 1 0 -1 0 -1 0 0 0 0 0; 0 0 1 0 0 0 -1 0 0 0 -1; 0 0 0 1 0 0 0 -1 0 0 0; 0 0 0 0 1 0 1 0 -1 0 0; 0 0 0 0 0 1 0 1 0 -1 0; 0.9 -0.1 0 0 0 0 0 0 0 0 0; 0 0 0 0 0 0 0 0 0.97 -0.03 0; 0 0 -1 0 0 0 1 0 0 0 0; 0 0 0.9 -0.1 0 0 0 0 0 0 0; 1 1 0 0 0 0 0 0 0 0 0]

 

b = [0 0 0 0 0 0 0 0 0 0 1000]

 

Note: use "copy and paste" when entering matrix "a" in MATLAB. I had to put this way to save your time. 

 

If you are familiar with MATLAB, could you please copy this m-file and try to run on your PC, then let me know what is the cause for this problem?

 

The m-file is

 

function x = Gauss(a,b)

% The function solve a system of linear equations [a][x]=[b] using the Gauss

% elimination method.

% Input variables:

% a The matrix of coefficients.

% b A column vector of constants.

% Output variable:

% x A colum vector with the solution.

ab = [a,b];

[R, C] = size(ab);

for j = 1:R-1

for i = j+1:R

ab(i,j:C) = ab(i,j:C)-ab(i,j)/ab(j,j)*ab(j,j:C);

end

end

x = zeros(R,1);

x(R) = ab(R,C)/ab(R,R);

for i = R-1:-1:1

x(i)=(ab(i,C)-ab(i,i+1:R)*x(i+1:R))/ab(i,i);

end

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