def f(self, y):
d = self.d<EOL>mpsi = self.psi<EOL>z = d * y.copy()<EOL>for i in range(len(mpsi)):<EOL><INDENT>a, b, c = mpsi[i]<EOL>z += a * np.tanh(b * (y + c))<EOL><DEDENT>return z<EOL>
Transform y with f using parameter vector psi
psi = [[a,b,c]]

:math:`f = (y * d) + \\sum_{terms} a * tanh(b *(y + c))`