opticalmaterialspy/_material_base.py
def ng(self, wavelength):
        '''
        The group index with respect to wavelength.

        Args:
            wavelength (float, list, None): The wavelength(s) the group
                index will be evaluated at.

        Returns:
            float, list: The group index at the target wavelength(s).
        '''
        return self.n(wavelength) - (wavelength*1.e-9)*self.nDer1(wavelength)
def ng(self, wavelength):
        '''
        The group index with respect to wavelength.

        Args:
            wavelength (float, list, None): The wavelength(s) the group
                index will be evaluated at.

        Returns:
            float, list: The group index at the target wavelength(s).
        '''
        return self.n(wavelength) - (wavelength*1.e-9)*self.nDer1(wavelength)
The group index with respect to wavelength.

        Args:
            wavelength (float, list, None): The wavelength(s) the group
                index will be evaluated at.

        Returns:
            float, list: The group index at the target wavelength(s).