The discrete-time filter behaves at frequency formula_63 the same way that the continuous-time filter behaves at frequency formula_64. Specifically, the gain and phase shift that the discrete-time filter has at frequency formula_63 is the same gain and phase shift that the continuous-time filter has at frequency formula_66. This means that every feature, every "bump" that is visible in the frequency response of the continuous-time filter is also visible in the discrete-time filter, but at a different frequency. For low frequencies (that is, when formula_67 or formula_68), then the features are mapped to a "slightly" different frequency; formula_69.