How to subtract an (n by m) matrix from an (n by m) by k matrix without looping?

Suppose I have the following matrices:

A=[1:4;5:8]
B=randi(10,2,4,3);

I want the same result as the code below gives but without looping, as I intend to use significantly larger sized dimensions which is very slow using looping.

for i=1:3
C(:,:,i)=B(:,:,i)-A;
end

Another method I tried was to concatenate matrix A with itself so that both A and B were the same dimensions before subtraction, but storing A for large dimensions is very memory consuming, not to mention unnecessary.

Cheers.

Answer 1

[dpb]

>> a=eye(2);
>> b=rand(2,2,2)
b(:,:,1) =
  0.3500    0.9275
  0.2871    0.0513
b(:,:,2) =
  0.5927    0.8384
  0.1629    0.1676
>> bsxfun(@minus,b,a)
ans(:,:,1) =
 -0.6500    0.9275
  0.2871   -0.9487
ans(:,:,2) =
 -0.4073    0.8384
  0.1629   -0.8324
>>

Answer 2

[Azzi Abdelmalek]

C=bsxfun(@minus,B,A)

Answer 3

[Chris Turnes]

While bsxfun is the preferred method for doing this, for the sake of completeness in answering the question you can also use indexing:

>> a = eye(2);
>> b = rand(2,2,2);
>> b-a(:, :, ones(2,1))

ans(:,:,1) =

     -0.6251    0.8531
      0.8449   -0.0829

ans(:,:,2) =

     -0.7962    0.6896
      0.5438   -0.6952