putBinA(A,B,x,y)

function out = putBinA(A,B,x,y)
% Function that places a small 2D matrix "B" into a larger one "A"
% with UL corner at coordinates (x,y). If the input args are given, then
% x is expected to be a 2 letter code for one of the nine
% standard locations in "A" (UL, UC, UR, ML, MC, MR, LL, LC, LR).

codes = {'UL', 'UC', 'UR', 'ML', 'MC', 'MR', 'LL', 'LC', 'LR'};
bx = size(B,1); by = size(B,2);

% check the input arguments are valid
if (nargin > 2) && (nargin < 5)
    % check that A and B are 2D matricies
    if (numel(size(A))~=2) || (numel(size(B))~=2)
        error('The input matricies must be 2D arrays');
    end
    % check that A is >= B on both dims
    if (size(A,1)<size(B,1)) || (size(A,2)<size(B,2))
        error('The "A" matrix size must be >= the "B" matrix size');
    end
    if nargin == 3
        coords = false;
        y = 0;
        % check that x is a 2 letter code
        if size(strmatch(x,codes,'exact'))==[0 0]
            error('The 2 letter code is incorrect');
        end
    else
        % check that x and y are integers
        if isnumeric(x) && isnumeric(y)
            coords = true;
            % check that the x,y placement lands B entirely contained in A
            if (size(A,1) < (x+bx)) || (size(A,2) < (y+by))
                error('The "B" matrix will fall outside of "A" with these coordinates');
            end
        end
    end
else
    error('Function putBinA expects either 3 or 4 input arguments');
end

out = A;

% Place B in A at (x,y) position
if coords
    xx = x + bx - 1;
    yy = y + by - 1;
    out(x:xx,y:yy) = B;
else
    % put B at the coded location
end