CODEWITHSUNDEEP
arraysmatlab
user1292919
user1292919

Reputation: 193

Create 3d matrix from 3 vectors

I have 3 vectors, named a, b and c and I want to create 3D matrix, M, so that M(i,j,k) = a(i) + b(j) + c(k), where a(i) means ith element of vector a, and likewise for all vectors and matrix.

For creating 2d matrix, it is easy like a+b'. but I am not sure how I can create 3d matrix.

Upvotes: 1

Views: 814

Answers (1)

Luis Mendo
Luis Mendo

Reputation: 112759

You only need permute or reshape to do the multi-dimensional equivalent of transposition:

a + b.' + reshape(c, 1, 1, []);

Assuming that a, b, c are column vectors of sizes L×1, M×1 and N×1, this works because

  • a is L×1, or equivalently L×1×1;
  • b.' is 1×M×1;
  • reshape(c, 1, 1, [] is 1×1×N.

So, by implicit expansion the result is an L×M×N 3D array.

Upvotes: 4

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