The first time this method is called, the
.__mInverse attribute will be
None, as it was initialized in the constructor. At that
point we compute the matrix inverse of
self.__m and store it there for future reuse.
In NumPy, matrix inversion is the function
inv() in the linear algebra submodule
# - - - X f o r m . i n v e r s e def inverse ( self ): '''Return the inverse transform as an Xform. ''' #-- 1 -- # [ if self.__mInverse is None -> # self.__mInverse := matrix inverse of self.__m # else -> I ] if self.__mInverse is None: self.__mInverse = num.linalg.inv ( self.__m ) #-- 2 -- return Xform(self.__mInverse)