FUNCTION Centroid, array ndim = Size(array, /N_Dimensions) IF ndim NE 2 THEN BEGIN Message, 'Array must be two-dimensional. Returning...', /Informational RETURN, -1 ENDIF s = Size(array, /Dimensions) totalMass = Total(array) xcm = Total( Total(array, 2) * Indgen(s[0]) ) / totalMass ycm = Total( Total(array, 1) * Indgen(s[1]) ) / totalMass RETURN, [xcm, ycm] END