Matlab – How to detect if I’m running MATLAB or Octave

There are four ways how Matlab code gets sped up:

• JIT: compiling at runtime helps with loops but seems to speed up (or at least interact with) other parts of the code as well, according to my anecdotal observations.

• Implementing functions in C/C++: There's a bunch of Matlab/Octave functions that are implemented in Matlab/Octave. At every release, there's a bunch more of them that get made into built-ins.

• Multithreading: There's a list of functions that have multithreaded implementations, which will speed up function calls.

• Generally more efficient implementations. For example the median filter got a massive speed boost for integer inputs a few releases ago.

All of these approaches need developers dedicated to make code faster. As far as I know, a major concern of Octave developers is to make sure (Matlab) functionality is there at all, whereas performance increase seems to have been a focus of Matlab development in the last few years.

First of all, you are not defining your function correctly, as the function does not know what M is (unless it is a global vairable, but I doubt so).

In ANY programming language, you need to tell a function which variables it is going to work with. This is not Matlab specific. In Matlab you will do it so:

function mean_DNA_Microarray = Calc_mean_DNA_Microarray(M)  % Look! we are telling him what M is!
    mean_DNA_Microarray = M - ones(5,25)*mean(M(:,25)) 
end

Then you want to all the function from somewhere else you would need to just type its name and pass in the arguments, in this case what inside the function is going to be called M

clear;
clc;
% Test code
Mnameoutofthefunction=rand(100,100);
DNAmean = DNA_Microarray(Mnameoutofthefunction); % here we are calling it!

Remember to save the function as functionname.m , in your case DNA_Microarray.m , else Matlab wont know which one it is.

But I HIGHLY recommend you to read a book about Matlab or just about programming in general, as it seems like you could benefit from some basic introduction.

Following @am304 suggestion, here you can find nice tutorials:

http://www.mathworks.co.uk/academia/student_center/tutorials/

EDIT What you want to do is create a function as follows:

function mean_DNA_Microarray = Calc_mean_DNA_Microarray(M)  % Look! we are telling him what M is!
    mean_DNA_Microarray = M - ones(5,25)*mean(M(:,25)) 
end

And then, inside your function DNA_Microarray call Calc_mean_DNA_Microarray with the input M