C function in Matlab [Mex-file]

Can someone help me with C function in Matlab? I did these code and my professor wanted me to do in C function in matlab. And is there any good websites that i can learn about matlab functions etc too? thank you.

I = imread('C:\OUTDOOR\456kg.jpg'); %read the image
subplot(3,3,1);imshow(I);
gray = rgb2gray(I);    %convert to grayscale
subplot(3,3,2); imshow(gray)

u=fspecial('unsharp',1);
pu=filter2(u,gray);
subplot(3,3,3); imshow(pu/255)

Binary = pu<24;      %find a suitable threshold
subplot(3,3,4); imshow(Binary)
Binary = ~Binary;      %complement the image
subplot(3,3,5); imshow(Binary)
imwrite(Binary, 'C:\INDOOR\456kgnew.jpg','jpg')

I=imread('C:\INDOOR\456kgnew.jpg'); %read the image

J = imread('C:\INDOOR\456kgnew.jpg');
K = imnoise(J,'salt & pepper',0.02);
L = medfilt2(K);
subplot(3,3,6); imshow(L);

[EDITED, Jan, code formatted]

[Jan]

As long as you do not ask a qeustion, it is hard to help. What is the problem?

[Esther]

my professor wanted me to write in functions. which i do not get what he means too. maybe like C programming?

Answer 1

[Jan]

A function has its own "workspace", which is the set of locally known variables. As explained in the documentation exhaustively (reading the "Getting Started" chapters is recommended!), your can write a function like this:

function [output1, output2, ...] = FunctionName(input1, input2, ...)

"Scripts" are similar, but do not have the above line and they share the workspace of the calling function or script.

For your example:

function MyDisplayFunction(FileName)
I = imread(FileName)
...

Then this is called from the command window or any other function as:

MyDisplayFunction('C:\OUTDOOR\456kg.jpg')

[Esther]

was it this? http://www.mathworks.com/videos/getting-started-with-matlab-68985.html

[Jan]

I thought of http://www.mathworks.com/help/matlab/getting-started-with-matlab.html or the correcponding chapters in your local docs.