How to optimize this code?Please help me and guide me in this direction.

hist11=zeros(256,1); hist12=zeros(256,1); hist13=zeros(256,1); hist21=zeros(256,1); hist22=zeros(256,1); hist23=zeros(256,1); hist31=zeros(256,1); hist32=zeros(256,1); hist33=zeros(256,1); using for loop ?Is there any other approach other than for loop?Please help me and guide me in this direction.

[Elias Gule]

Are you trying to generate a 3 x 3 matrix whose elements are each 256 x 1 matrices? If that's the case then I'll send an answer shortly.

[Image Analyst]

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

[Adam]

Adding words like "as soon as possible" is more likely to turn people away from answering your question than get people to hurry up!

[John D'Errico]

Yes. The "as soon as possible" addition usually turns me off, as it tends to imply that our time is of less value than the person asking the question.

Answer 1

[John D'Errico]

Or a 3-d array, if your goal is to have them in the same shape as your numbered array names have them?

allHists = zeros(256,3,3);

Now, when you wanted to access hist13, you just use

allHists(:,1,3)

The nice things is all of your arrays are in one place. You can operate on them as an entire array. You can create arrays with many such histograms in them. And you can even access them programmatically, in a loop, for example.

Answer 2

[Elias Gule]

To store matrices in a matrix you need to use a cell array. A cell array is capable of storing any data type. Hence we are first going to create a 3 x 3 cell array of empty cells; then in each empty cell, we will place a cell array containing a matrix of 256 x 1 zeros; If we tried to put the matrices in a single matrix we would end up with a concatenation of these matrices to a single 768 x 768 matrix.

%% Code begins

hist_ = cell(3,3);

hist_(1:end) = {zeros(256,1)};

Answer 3

[Image Analyst]

Why not use a simple 2d numerical array:

theHists = zeros(256, 9);

[Elias Gule]

this will only create a matrix of size 256 x 9; if you type hist(1), you get 0 as an answer; which is not what is required. what he/she wanted was a matrix 3 by 3 matrix whose items are each 256 by 1 column vectors.