distances.py 文件源码

def _calculate(self):
        min_, max_ = self._bounds
        n = np.prod(self.reference.shape)
        f = n * (max_ - min_)**2

        diff = self.other - self.reference
        value = np.vdot(diff, diff) / f

        # calculate the gradient only when needed
        self._g_diff = diff
        self._g_f = f
        gradient = None
        return value, gradient