Perl AI Deep Learning Tutorial

Derivative of sigmoid function

Let's write the derivative of sigmoid function in Perl. A derivative is a derivative of a function. The derivative of the sigmoid function is used for the inverse mispropagation method.

#Derivative of sigmoid function
sub sigmoid_derivative {
   my ($x) = @_;
  
   my $sigmoid_derivative = sigmoid ($x) * (1 --sigmoid ($x));
  
   return $sigmoid_derivative;
}

#Sigmoid function
sub sigmoid {
   my ($x) = @_;
  
   my $sigmoid = 1.0 / (1.0 + exp(-$x));
  
   return $sigmoid;
}

my $x = 0.5;
my $sigmoid_derivative = sigmoid_derivative ($x);

# 0.2350037122015944890693
print "$sigmoid_derivative\n";