def getIdentityMatrixTetragrid(tetragrid=None):
 if (tetragrid == None):
  return [[1.0, 0.0, 0.0, 0.0], [0.0, 1.0, 0.0, 0.0], [0.0, 0.0, 1.0, 0.0], [0.0, 0.0, 0.0, 1.0]]
 return tetragrid

def getIdentityMatrixTetragrid ( tetragrid = None ) : if ( tetragrid == None ) : return [ [ 1.0 , 0.0 , 0.0 , 0.0 ] , [ 0.0 , 1.0 , 0.0 , 0.0 ] , [ 0.0 , 0.0 , 1.0 , 0.0 ] , [ 0.0 , 0.0 , 0.0 , 1.0 ] ] return tetragrid
get four by four matrix with diagonal elements set to one .