MATLAB: Matlab help with coding

What would be the code to compute the maximum value of column 1 that is less than 200?

The numbers are

1 5 600

2 5 155

8 5 234

3 5 100

A = [1 5 600 
     2 5 155
     8 5 234
     3 5 100];
 maxval = max(A(A(:,1)<200,1))

If you want to change which column you search for, then change the 1's to the corresponding column number (e.g. maxval_col3 = max(A(A(:,3)<200,3))

What do you want to do with the 600? Delete it (making the vector shorter)? replace it with a different number? replace it with a char?

Suppose your matrix is called "M1", and your maximal value is MAXVAL,

M1(M1>MAXVAL)=[ ]; %to remove

M1(M1>MAXVAL)=-1; %to replace it with a value

Use imdilate() if you have the Image Processing Toolbox. It's a moving max filter

kernel = [1;1;1;1;1];  % Vertical 5 by 1 filter.
result = imdilate(yourArray, kernel);

yourArray can be a 1 or 2 D array.