Computing A(:, m)*B(m, :) without a for loop

1 visualizzazione (ultimi 30 giorni)
Nicolas Perez
Nicolas Perez il 12 Nov 2018
Commentato: Nicolas Perez il 12 Nov 2018
Provided I have two matrices A and B of dimensions NxM and MxN I want to compute a matrix C of dimensions NxNxM such that each NxN slice is the result of the prduct A(:, m)*B(m, :). I know this can be obtained in the following way:
for m=1:M
C(:, :, m) = A(:, m)*B(m, :);
end
Is there a way of obtaining the same result without using a for loop (with the aim of making the computation faster)?

Risposta accettata

Matt J
Matt J il 12 Nov 2018
Ar=reshape(A,N,1,[]);
Br=reshape(B.',1,N,[]);
C=Ar.*Br;

Più risposte (1)

madhan ravi
madhan ravi il 12 Nov 2018
C(:, :, 1:M) = A(:, 1:M)*B(1:M, :);
  1 Commento
Nicolas Perez
Nicolas Perez il 12 Nov 2018
The output of A(:, 1:M)*B(1:M, :); is the sum of C(:, :, 1:M) along the third dimension (an NxN matrix). Thus, you get the "Assignment has fewer non-singleton rhs dimensions than non-singleton subscripts" error.

Accedi per commentare.

Categorie

Scopri di più su Chemistry in Help Center e File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by