Construct from angle

* Construct from real part and three imaginary parts. * Quaternion is normalized after construction. */

Args: num_clusters : int The number of clusters dim : int Dimension of descriptors

Select the backend NOTE:** This must be called before the first plot command to have any effect. Mainly useful to select the non-interactive 'Agg' b

@name Helper functions { * Calculate the exponential map. In matrix terms this would correspond * to the Rodrigues formula. */ FIXME vectview<> c

前向传播函数，计算VLAD向量

前向传播