Matlab's bsxfun() code

Question

What does this do?

u = [5 6];
s = [1 1];
data1    =[randn(10,1) -1*ones(10,1)];
data2    =[randn(10,1) ones(10,1)];
data     = [data1; data2];
deviance = bsxfun(         


        

Answer 1

The function BSXFUN will perform the requested element-wise operation (function handle argument) by replicating dimensions of the two input arguments so that they match each other in size. You can avoid the use of BSXFUN in this case by replicating the variables u and s yourself using the function REPMAT to make them each the same size as data. Then you can use the standard element-wise arithmetic operators:

u = repmat(u,size(data,1),1);  %# Replicate u so it becomes a 20-by-2 array
s = repmat(s,size(data,1),1);  %# Replicate s so it becomes a 20-by-2 array
deviance = ((data-u)./s).^2 + 2.*log(abs(s));  %# Shortened to one line