class CooCoo::CostFunctions::CrossEntropy

Implements the log cross-entropy cost function that is used with {ActivationFunctions::SoftMax} and {ActivationFunctions::ShiftedSoftMax}. This calls Math.log on the network's output and multiples that by the target. Therefore good target values are 0...1.

Public Class Methods

call(target, x) click to toggle source
# File lib/coo-coo/cost_functions.rb, line 65
def self.call(target, x)
  -x.log * target
end
derivative(target, x) click to toggle source
# File lib/coo-coo/cost_functions.rb, line 69
def self.derivative(target, x)
  -target / x
end