MATLAB: How to generate a random 2×2 matrix with values in the range −1 to 1

matrixrandom

Hi, I'm new to matlab and trying to generate a random 2×2 matrix with values in the range -1 to 1.

Thank you for your time.

Best Answer

This works:

M = 2*rand(2)-1;

Related Solutions

MATLAB: Creating a Matrix of random numbers

possibleValues = [-1, 1];
desiredSize = [5 6];
A = possibleValues(randi(numel(possibleValues), desiredSize))
A = 5×6
    -1     1     1     1     1    -1
    -1    -1     1     1    -1    -1
    -1    -1    -1     1    -1    -1
     1     1    -1     1     1    -1
    -1     1    -1     1     1    -1

This assumes you want -1 and 1 to be equally likely. If you need an exact number of each possible value:

elements = [repmat(-1, 1, 5), repmat(1, 1, 25)];
order = randperm(numel(elements));
shuffled = reshape(elements(order), desiredSize)
shuffled = 5×6
     1    -1     1     1     1     1
     1     1     1     1    -1     1
     1     1    -1     1     1     1
    -1     1     1     1     1     1
    -1     1     1     1     1     1
●

If you need the two numbers not to be equally likely (say 1 three times as likely as -1) there are ways to do this as well.

MATLAB: Matrix[1,1,1,1;-1,-1,-1,-1;1,1,1,1] to vector[1,1,1,1,-1,-1,-1,-1,1,1,1,1]

I believe you intended semicolons (;) instead of colons (:) in your matrix definition.

To convert it to a vector, use the reshape function:

Matrix = [1,1,1,1; -1,-1,-1,-1; 1,1,1,1];
Vector = reshape(Matrix', 1, [])
Vector =
       1     1     1     1    -1    -1    -1    -1     1     1     1     1

EDIT — Added output of ‘Vector’.

Best Answer

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MATLAB: Creating a Matrix of random numbers

MATLAB: Matrix[1,1​,1,1;-1,-1​,-1,-1;1,1​,1,1] to vector[1,1​,1,1,-1,-1​,-1,-1,1,1​,1,1]

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MATLAB: Matrix[1,1,1,1;-1,-1,-1,-1;1,1,1,1] to vector[1,1,1,1,-1,-1,-1,-1,1,1,1,1]