func (_ SigmoidCECost) Cost(x linalg.Vector, a autofunc.Result) autofunc.Result {
logsig := autofunc.LogSigmoid{}
log := logsig.Apply(a)
invLog := logsig.Apply(autofunc.Scale(a, -1))
xVar := &autofunc.Variable{x}
oneMinusX := autofunc.AddScaler(autofunc.Scale(xVar, -1), 1)
sums := autofunc.Add(autofunc.Mul(xVar, log), autofunc.Mul(oneMinusX, invLog))
return autofunc.Scale(autofunc.SumAll(sums), -1)
}
func (_ SigmoidCECost) CostR(v autofunc.RVector, x linalg.Vector,
a autofunc.RResult) autofunc.RResult {
logsig := autofunc.LogSigmoid{}
log := logsig.ApplyR(v, a)
invLog := logsig.ApplyR(v, autofunc.ScaleR(a, -1))
xVar := autofunc.NewRVariable(&autofunc.Variable{x}, v)
oneMinusX := autofunc.AddScalerR(autofunc.ScaleR(xVar, -1), 1)
sums := autofunc.AddR(autofunc.MulR(xVar, log), autofunc.MulR(oneMinusX, invLog))
return autofunc.ScaleR(autofunc.SumAllR(sums), -1)
}