MATLAB: DOT type element wise multiplication of two 2-D matrices with array expansion (3-D)

array expansionmatrix multiplications

I have two 2-d matrices A(100*20) and B(20*100). I want to perform multiplication of each row of A with each column of B element wise and store the result in a 3-d matrix. How can I perform it? Thanks in advance.

Best Answer

out3D = A .* permute(B,[3,1,2]); % for R2016a and later
out3D = bsxfun(@times,A, permute(B,[3,1,2])); % earlier R2016a

Related Solutions

MATLAB: Cell array expansion

This is the standard behaviour of Matlab:

x = {1, 2};
y = x{:};   % y is x{1}

You see the same method for:

a = rand(1, 10);
b = max(a);

Why is this equivalent? Because MAX replies 2 outputs as "x{:}" and if just the 1st is caught, the 2nd is ignored. Therefore these methods are equivalent also:

x = {1, 2};
[y1, y2] = x{:}
a = rand(1, 10);
[b1, b2] = max(a)

So I would not expect an MLint-warning for a standard behaviour.

MATLAB: Taylor series method expansion

function D = dy(x,y)
  f = x^2+y^2;
  df = 2*x+2*y*f;
  d2f = 2+2*(f^2+y*df);
  d3f = 2*(2*f*df+f*df+y*d2f);
  d4f = 2*(2*(df^2+f*d2f)+df^2+f*d2f+f*d2f+y*d3f);
  D = [f df d2f d3f d4f];
end

suggest me to change the above code as given below, so that the differentiation is calculated by using diff function, without giving the differentiation directly in the program.

function D = dy(x,y)
  f = x^2+y^2;
  df = diff(f);
  d2f = diff(df);
  ---
  ---

Best Answer

Related Solutions

MATLAB: Cell array expansion

MATLAB: Taylor series method expansion

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