how to define a function in matlab so that we can call it?

e.g. function [e,w]=blocklms (mu,M,u,d);

Answer 1

[Stephen23]

Basic function syntax is like this:

function [e,w] = blocklms(mu,M,u,d)
% Your code here:
e = mu*M;
W = u-d;
%
end

Save this in an M-file with the same name as the function itself, and then you can call your function from the command line, a script, or from any other function. For more information read the documentation, which also includes lots of nice examples:

http://www.mathworks.com/help/matlab/ref/function.html