How can I apply a function for more than one matrix?

Question

alexp10 2020-5-1

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/522321-how-can-i-apply-a-function-for-more-than-one-matrix

评论： Image Analyst 2020-5-3

I'm trying to check if all these matrices A,B,C & D can be made diagonally dominant by swapping rows and if they CAN, store that matrix as M_A , M_B, M_C and M_D. So far it works for A but I have no idea how to do it for all the other matrices and get the result at once. I also can't get the diagonally dominant matrix to be stored as M_A. Any help would be much appreciated!!!

(CODE BELOW)

function [ M, M_A ] = DiagDom
A =  [ 1 4 0 1 1; -1 -5 9 -20 2 ; 15 1 4 5 1 ; 2 2 -5 0 0; 0 2 -3 1 -9];
B= [ 9 3 3; 12 3 2; 1 3 5];
C= [ 1 13 2; 1 3 9; -12 2 -1];
D= [ 5 -2 4 2; 0 3 -1 -1; 3 3 9 -5;1 1 1 5];
M = {A,B,C,D}; 
for i=1:numel(M)
    count = 0;
    while(1) % Perform infinite loop, till you find the diagonally dominant matrix
        if itisDiagDom (M{i}) % If this is diagonally dominant, disp and break the loop
            disp (['Matrix M is diagonally-dominant']);
            celldisp(M) ; 
            disp([count]);
            break;
        else
            M{i} = M{i}(randperm(size(M{i}, 1)), :);
            count= count+1 ;
             disp([count]); 
         if count > 500
             
             M_A= M{1};
             M_B= M{2};
             M_C= M{3};
             M_D= M{4};
             disp('M_A is');
             disp(M_A);
             disp('M_B is');
             disp(M_B);
             disp('M_C is');
             disp(M_C);
             disp('M_D is');
             disp(M_D); 
             break ; 
         end
             % Randomly swaps rows
        end
    end
    
end
end 
function [isdom] = itisDiagDom( A ) 
isdom = true;
for r = 1:size(A,1)
    rowdom = 2 * abs(A(r,r)) > sum(abs(A(r,:)));
    isdom = isdom && rowdom;
end
if isdom == 0
    
   
    disp (['Matrix']);
    disp([A]);
    disp([' is not diagonally-dominant']);
    
elseif isdom == 1
        disp (['Matrix A is diagonally-dominant']);
         disp([A]);
       
  
end
end

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Answer 1

Ameer Hamza 2020-5-2

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/522321-how-can-i-apply-a-function-for-more-than-one-matrix#answer_429844

在 MATLAB Online 中打开

This function shows how to save all process and return the output as a cell array

function [ M, M_A ] = DiagDom
A =  [ 1 4 0 1 1; -1 -5 9 -20 2 ; 15 1 4 5 1 ; 2 2 -5 0 0; 0 2 -3 1 -9];
B= [ 9 3 3; 12 3 2; 1 3 5];
C= [ 1 13 2; 1 3 9; -12 2 -1];
D= [ 5 -2 4 2; 0 3 -1 -1; 3 3 9 -5;1 1 1 5];
M = {A,B,C,D};
M_A = cell(1,numel(M));
for i=1:numel(M)
    while(1) % Perform infinite loop, till you find the diagonally dominant matrix
        if IsDiagDom (M{i}) % If this is diagonally dominant, disp and break the loop
            disp (['Matrix A is diagonally-dominant']);
            M_A{i} = IsDiagDom (M{i}) ;
            break;
        else
            M{i} = M{i}(randperm(size(M{i}, 1)), :); % Randomly swaps rows
        end
    end
end

However, the current loop code gets stuck for matrix B and keeps printing "Matrix A is not diagonally-dominant". You may need to check your algorithm.

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Ameer Hamza 2020-5-3

在 MATLAB Online 中打开

It is better to use cell array, then using separate names for the variables. See here why creating different variable names is a bad idea: https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval. If you still want to create M_A, M_B, .. then you can do it like this.