type change8to9.m

function [output] = change8to9( inputMatrix)
%changes the first 8 in each row to a 9 in a matrix and returns that altered matrix
%input: matrix
%output: matrix
     lengths = size(inputMatrix); %get size of matrix and store in 1x2 array
     fprintf('size of the matrix m by n is ')
     disp(lengths)
     for m = 1:lengths(1)
         for n = 1:lengths(2)
             if  (inputMatrix(m,n) == 8) %if that position equals an 8
		 inputMatrix(m,n) = 9;  %change that position in the matrix to a 9 using an assignment statement
		 break; %break out of this inner FOR loop
             end  %ends the IF
         end  %ends the inner FOR loop
     end   %ends the outer FOR loop
     output = inputMatrix; %assign the matrix to the output value (or in other words, "return the (possibly) altered matrix")
end %end the function
     

%Note, this function changes the first 8 in each row to a 9. while only the first? 
matrixA = [1 2 3; 4 5 6; 7 8 9; 8 8 8 ; 8 1 1; 8 0 8]

matrixA =

     1     2     3
     4     5     6
     7     8     9
     8     8     8
     8     1     1
     8     0     8

change8to9(matrixA)
size of the matrix m by n is      6     3


ans =

     1     2     3
     4     5     6
     7     9     9
     9     8     8
     9     1     1
     9     0     8

%notice the first 8 in each row is now a 9
%if we look at matrixA again
matrixA

matrixA =

     1     2     3
     4     5     6
     7     8     9
     8     8     8
     8     1     1
     8     0     8

%it hasn't changed!
%that's because we didn't assign anything to it and once it is copiied into the function, the function then alters the copy. not the original matrix
%the following assignment statement would change it
matrixA = change8to9(matrixA)
size of the matrix m by n is      6     3


matrixA =

     1     2     3
     4     5     6
     7     9     9
     9     8     8
     9     1     1
     9     0     8

matrixA

matrixA =

     1     2     3
     4     5     6
     7     9     9
     9     8     8
     9     1     1
     9     0     8

%and we can repeat this process and turn every 8 into a 9
matrixA = change8to9(matrixA)
size of the matrix m by n is      6     3


matrixA =

     1     2     3
     4     5     6
     7     9     9
     9     9     8
     9     1     1
     9     0     9

matrixA = change8to9(matrixA)
size of the matrix m by n is      6     3


matrixA =

     1     2     3
     4     5     6
     7     9     9
     9     9     9
     9     1     1
     9     0     9

matrixA

matrixA =

     1     2     3
     4     5     6
     7     9     9
     9     9     9
     9     1     1
     9     0     9

diary off