Vectorized operations on multidimensional arrays

Hi,

Say, there is 3D array a:

a(:,:,1) =

    56   123
    48   242

a(:,:,2) =

   206    30
   188    26

a(:,:,3) =

   251   138
   167     8

And 3D array m:

m(:,:,1) =

   117.2500

m(:,:,2) =

   112.5000

m(:,:,3) =

   141

How do I subtract m(:,:,1:3) from a(:,:,1:3) in a vectorized manner? I.e. do something like

for k=1:length(a), res(:,:,k)=a(:,:,k)-m(:,:,k); end

The result should be:

res(:,:,1) =

   -61.2500    5.7500
   -69.2500  124.7500

res(:,:,2) =

   93.5000  -82.5000
   75.5000  -86.5000

res(:,:,3) =

   110    -3
    26  -133

Thank you!

Answer 1

[Andrei Bobrov]

res = bsxfun(@minus,a,m)

please read about function bsxfun

[Mikhail]

Awesome, thanks! Now, how about if m was as following?

m =

117.2500 112.5000 141

[Andrei Bobrov]

res = bsxfun(@minus,a,reshape(m,1,1,[]))

or

res = bsxfun(@minus,a,permute(m,[1 3 2]))

please read:

http://www.mathworks.com/help/techdoc/ref/reshape.html

http://www.mathworks.com/help/techdoc/ref/permute.html

[Mikhail]

Thanks again!