def _der(self, x):
    '\n        Returns the first derivative of the function at each value in x.  Only\n        called internally by HARKinterpolator1D.derivative.\n        '
    (y, dydx) = self.eval_with_derivative(x)
    return dydx
Returns the first derivative of the function at each value in x.  Only
called internally by HARKinterpolator1D.derivative.
def _der(self, x):
    '\n        Returns the first derivative of the function at each value in x.  Only\n        called internally by HARKinterpolator1D.derivative.\n        '
    (y, dydx) = self.eval_with_derivative(x)
    return dydx