argmin function for Matlab® vectors, matrices, and datacubes

argmin.m

function [ arg_min, minimum ] = argmin( A, dim )
%ARGMIN Find the argmin of a vector, matrix or datacube.
%   A is the vector, matrix or data cube for which we want to find the
%   minimum and the argument of the minimum.
%   dim is the dimension of the data structure.

    %% Error check for arguments
    if dim > 3; error('Dimension must be 1 =< dim =< 3'); end
    if dim < 1; error('Dimension must be 1 =< dim =< 3'); end
    if isnan(A); error('A must be real'); end
    if isinf(A); error('A must be real'); end
    if ~isreal(A); error('A must be real'); end
    
    
    if dim == 1
        [minimum,arg_min] = min(A);
        return
    elseif dim == 2
        [minNxN,argminNxN] = min(A);
        [min1xN,argmin1xN] = min(minNxN);
        minimum = min1xN;
        arg_min = [argminNxN(argmin1xN) argmin1xN];
        return
    elseif dim == 3
        [minNxNxN,argminNxNxN] = min(A);
        [minNxNx1,argminNxNx1] = min(minNxNxN);
        [minNx1x1,argminNx1x1] = min(minNxNx1);
        minimum = minNx1x1;
        arg_min = [argminNxNxN(1,argminNxNx1(argminNx1x1),argminNx1x1) ...
            argminNxNx1(argminNx1x1) argminNx1x1];
    end

end