A VectorClassifier in which the score for each class is a dot-product between the observed feature vector and a vector of parameters. Examples include NaiveBayes, MultivariateLogisticRegression, LinearSVM, and many others. Counter-examples include KNearestNeighbor.
Put gradient of objective with respect to parameters into the accumulator.
Put gradient of objective with respect to parameters into the accumulator. The contract states we cannot mutate the "input" argument inside this method.
Accumulator to hold gradient
Weight mutliplier for gradient