set_activation Subroutine

  pure elemental subroutine set_activation(self, activation)
    !! Sets the activation function. Input string must match one of
    !! provided activation functions, otherwise it defaults to sigmoid.
    !! If activation not present, defaults to sigmoid.
    class(layer_type), intent(in out) :: self
    character(len=*), intent(in) :: activation
    select case(trim(activation))
      case('gaussian')
        self % activation => gaussian
        self % activation_prime => gaussian_prime
        self % activation_str = 'gaussian'
      case('relu')
        self % activation => relu
        self % activation_prime => relu_prime
        self % activation_str = 'relu'
      case('sigmoid')
        self % activation => sigmoid
        self % activation_prime => sigmoid_prime
        self % activation_str = 'sigmoid'
      case('step')
        self % activation => step
        self % activation_prime => step_prime
        self % activation_str = 'step'
      case('tanh')
        self % activation => tanhf
        self % activation_prime => tanh_prime
        self % activation_str = 'tanh'
      case default
        self % activation => sigmoid
        self % activation_prime => sigmoid_prime
        self % activation_str = 'sigmoid'
    end select
  end subroutine set_activation