Martin Reinecke committed Aug 19, 2017 1 2 3 4 5 6 ``````from nifty.energies.energy import Energy from nifty.energies.memoization import memo class QuadraticEnergy(Energy): """The Energy for a quadratic form. `````` Martin Reinecke committed Aug 19, 2017 7 8 `````` The most important aspect of this energy is that its curvature must be position-independent. `````` Martin Reinecke committed Aug 19, 2017 9 10 `````` """ `````` Martin Reinecke committed Aug 20, 2017 11 `````` def __init__(self, position, A, b, grad=None): `````` Martin Reinecke committed Aug 19, 2017 12 13 14 `````` super(QuadraticEnergy, self).__init__(position=position) self._A = A self._b = b `````` Martin Reinecke committed Aug 20, 2017 15 16 17 18 `````` if grad is not None: self._Ax = grad + self._b else: self._Ax = self._A(self.position) `````` Martin Reinecke committed Aug 19, 2017 19 20 21 22 `````` def at(self, position): return self.__class__(position=position, A=self._A, b=self._b) `````` Martin Reinecke committed Aug 20, 2017 23 24 25 26 `````` def at_with_grad(self, position, grad): return self.__class__(position=position, A=self._A, b=self._b, grad=grad) `````` Martin Reinecke committed Aug 19, 2017 27 28 29 30 31 32 33 34 35 36 37 38 39 `````` @property @memo def value(self): return 0.5*self.position.vdot(self._Ax) - self._b.vdot(self.position) @property @memo def gradient(self): return self._Ax - self._b @property def curvature(self): return self._A``````