3x3 matrix with while loop

Produce a random 3x3 matrix A that is invertible and display it. Hint: Use a while-loop until you get one with non-zero determinant. To create a random matrix with N rows and M columns,use the MATLAB command rand(N,M).

I know how to produce the 3x3 matrix and how to display it. I am just a little confused on how to use the while-loop. Can someone please help me?

[Alex Mcaulley]

determinant = 0;
while determinant == 0
    %Generate the random matrix
    %Calculate the determinant of that matrix
end

[Benjamin Trivers]

I made a script for this one, and it just ran forever

I need it to stop if the determinate = 0

Answer 1

[Jeremy]

n = 3; m = 3;
A = zeros(n,m);
while det(A) == 0
    A = rand(n,m);
end

[Benjamin Trivers]

close, but it is supposed to produce random matrices until the det = 0

this only produces one

[Jeremy]

"Use a while-loop until you get one with non-zero determinant"

The problem asks for an invertible matrix, meaning that the inverse exists. You are looking for a determinant that is not equal to zero.

A zero determinant would not be an invertible matrix (i.e., the inverse does not exist because the determinant is zero).

[Benjamin Trivers]

just a little confused. the end of the question stated "Use disp to print matrices" so i thought i was looking for more than one matrix

sorry just confused

[Jeremy]

Using rand, it's fairly unlikely that you'll create a matrix whose determinant is 0. It'd probably be easier to get a 0 determinant with randi

That being said, maybe running this will help you see what's going on

n = 3; m = 3;
A = zeros(n,m);
k = 0;
while det(A) == 0
    A = rand(n,m);
    k = k + 1;
    fprintf(1,'\nIteration Number %i \n',k)
    fprintf(1,' Matrix A = \n\n')
    disp(A)
    fprintf(1,'The Determinant of Matrix A is: \n')
    disp(det(A))
end

And if you wanted an (approximately) zero determinant:

n = 3; m = 3;
A = eye(n,m);
k = 0;
while abs(det(A)) > 0.001
    A = rand(n,m);
    k = k + 1;
    fprintf(1,'\nIteration Number %i \n',k)
    fprintf(1,' Matrix A = \n\n')
    disp(A)
    fprintf(1,'The Determinant of Matrix A is: \n')
    disp(det(A))
end

Using randi instead:

n = 3; m = 3;
A = eye(n,m);
k = 0;
while det(A) ~= 0
    A = randi([0 10],n,m);
    k = k + 1;
    fprintf(1,'\nIteration Number %i \n',k)
    fprintf(1,' Matrix A = \n\n')
    disp(A)
    fprintf(1,'The Determinant of Matrix A is: \n')
    disp(det(A))
end

I hope this helps