Writing a Matlab function for the first time

This is th first time I'm writing a Matlab function.I have written several FORTRAN programs earlier but not Matlab.

Now, my program essentially does (or I want it to do) the follwoing:

1) The function takes 3 arguments which are vectors. The 3 vectors are Params,X,Y

2) The program (or function) first gets the size of vectors X and Y respectively and assigns to variables xrows and yrows respectively

3) Now: actually the vectors X and Y are concatenated vectors. That is there may be 2 or more vectors (X1,X2,Y1,Y2,..) which are concatenated into X and Y the arguments

4) The program wants to split the vectors X and Y into X1,X2,Y1,Y2,X3,....

5) For the time beinmg ,I have defined the total number of concatenated vectors as total_sets inside the function.

6)I have written a code to get hthese concatenated vectors X1,X2,Y1,Y2 as below.Can anyone help me to do the encessary corrections to the code? I shall be grateful.

    function [ error ] = ConcatenatingAllDataSets( Params,X,Y)

    %UNTITLED Summary of this function goes here
    %   Detailed explanation goes here

    %Below we get the number of rows for the vector X

    xrows = size(X,1)

    %Below we get the number of rows for the vector Y

    yrows=size(Y,1)

    %Below we define the total number of sets that are to be concatenated

    %So, if total sets =1, it means that we will have one set of epsilon's
    %If total sets is equal to 2, we will have 2 sets of epsilons

    %Similarly, if total sets is equal to 

    total_sets=2

    start_value=0

    k=total_sets

    for j=1,total_sets

    for i=start_value+1,1,(xrows/k)

        epsilon(j,i)=X(i);
        sigma(j,i)=Y(i)

    end

    k=k-1

    end

    %Above we have separated concatenated values - X and Y separated into
    %epsilon and sigma

    end

Answer 1

[Andrew Newell]

I think what you are trying to do is convert a row vector into a matrix with total_sets number of rows. You can do this with two commands:

function [epsilon,sigma] = concatenatingAllDataSets(total_sets,X,Y)
epsilon = reshape(X,total_sets,[]);
sigma = reshape(Y,total_sets,[]);

(edited to add function statement)

[Shalini]

Yes, Andrew.Thanks a lot for that

I'm just very new to Matlab. Can you tell how to run the Matlab program to see if the function is doing what I wanted?

[Andrew Newell]

I added a function statement to my answer. Is that what you mean?

[Shalini]

Yes. How to see the values of epsilon and sigma on sceen?

[Shalini]

I get the following errors when I run the program:

??? Input argument "X" is undefined.

Error in ==> concatenatingAllDataSets at 3

epsilon = reshape(X,total_sets,[]);

??? Input argument "X" is undefined.

Error in ==> concatenatingAllDataSets at 3

epsilon = reshape(X,total_sets,[]);

??? Input argument "X" is undefined.

Error in ==> concatenatingAllDataSets at 3

epsilon = reshape(X,total_sets,[]);

Can you help pls?

[Andrew Newell]

Assuming you already have your vectors X and Y, you should run

total_sets = 2;

[epsilon,sigma] = concatenatingAllDataSets(total_sets,X,Y)

[Shalini]

I do not have the values yet.

I want to call this function by typing it in the command line and supplying the arguments.I want to check whether it does what I wanted it to.

I guess it is possible as I saw the video here: http://www.mathworks.in/support/2009a/matlab/7.8/demos/WritingAMATLABProgram.html

How to supply these vectors through command line?