scripts/builtin/sigmoid.dml

#-------------------------------------------------------------
#
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#-------------------------------------------------------------

# The Sigmoid function is a type of activation function, and also defined as a squashing function which limit the
# output to a range between 0 and 1, which will make these functions useful in the prediction of probabilities.
#
# INPUT:
# -------------------------------------------------------------------------------------------
# X      Matrix of feature vectors.
# -------------------------------------------------------------------------------------------
#
# OUTPUT:
# ------------------------------------------------------------------------------------------
# Y     1-column matrix of weights.
# ------------------------------------------------------------------------------------------

m_sigmoid = function(Matrix[Double] X) return (Matrix[Double] Y) {
  Y = 1 / (1 + exp(-X));
}

s_sigmoid = function(Double x) return (Double y) {
  y = 1 / (1 + exp(-x));
}