%testextract.m
%   Run this to test your extract function for EE435 Project 1. Note that
%   your error messages are probably not exactly the same as mine are, but
%   you should get errors when I do, and the returned matrix v should match
%   mine each time. This program assumes that the extract function has the
%   following usage:
%
%        y=extract(x,ulrow,ulcol,rows,cols)

x=eye(11);  %an 11 x 11 identity matrix
for k=2:11
    x(k,k)=x(k-1,k-1)+1;
end
% now matrix x has increasing integer values along main diagonal

v=extract(x,4,4,5,5)
disp('----------------------------------------------------------------')
% should display:
% v =
% 
%      4     0     0     0     0
%      0     5     0     0     0
%      0     0     6     0     0
%      0     0     0     7     0
%      0     0     0     0     8

pause
v=extract(x,2,3,4,4)
disp('----------------------------------------------------------------')

% should display:
% v =
% 
%      0     0     0     0
%      3     0     0     0
%      0     4     0     0
%      0     0     5     0
%       
pause
v=extract(x,5,6,3,3)
disp('----------------------------------------------------------------')

% should display:
% v =
% 
%      0     0     0
%      6     0     0
%      0     7     0
pause 

v=extract(x,5,6,4,6)
disp('----------------------------------------------------------------')

% should display:
% 
% v =
% 
%      0     0     0     0     0     0
%      6     0     0     0     0     0
%      0     7     0     0     0     0
%      0     0     8     0     0     0
%      
pause
v=extract(x,-1,6,2,2)
disp('----------------------------------------------------------------')

% should display an error message, like this:
% 
% Error: upperleft row or col number is off image, returning original image !
% 
% 
% v =
% 
%      []

pause
v=extract(x,1,6,13,7)
disp('----------------------------------------------------------------')

% should display an error message, like this:
% 
% Error: subimage > orig image size, returning NULL image !
% 
% 
% v =
% 
%      []