MATLAB: Operation without for loop

arraymatrix manipulation

I have two matrix.MAtrix A(250000×4)and MAtrix B(250000×4)

I have a function which result a scalar C.

    C = myfunction(X,Y);

Now i want to pass each row of MAtrixA and MAtrixB to myfunction without using a for loop.

How to do it ?

Best Answer

Y = arrayfun(@(i1)myfunction(A(i1,:), B(i1,:)), 1:size(A,1))

Related Solutions

MATLAB: Multiply each element of a vector with a matrix

BSXFUN!!!

B = [1 2; 3 4];
A = 1:5;
D = bsxfun(@times,B,reshape(A,1,1,numel(A)));

kron is notorious (at least in older versions) for being very slow.

And obligatory timings:

B = repmat([1 2; 3 4],10,10);
A = 1:50;
t1 = 0;
t2 = 0;
t3 = 0;
for ii = 1:100
      tic
      C = reshape(kron(A,B),[size(B),numel(A)]);
      t1=t1+toc;
      tic
      D = bsxfun(@times,B,reshape(A,1,1,numel(A)));
      t2=t2+toc;
      tic
      for indx = length(A):-1:1  % Backwards for pre-allocation
          result(:, :, indx) = A(indx) .* B;
      end
      t3=t3+toc;
  end
  isequal(C,D,result)
  [t1 t2 t3]
%{
ans =
     1
ans =
    0.0128    0.0069    0.0098
%}

MATLAB: Construct Power of Matrix without for loop

Example

A=magic(2);
N=3;
B=cell2mat(arrayfun(@(x) A^x,1:N,'un',0))

Best Answer

Related Solutions

MATLAB: Multiply each element of a vector with a matrix

MATLAB: Construct Power of Matrix without for loop

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