### First-Order Parallel Sections

Figure 3.13 shows the impulse response of the real one-pole section

`myfreqz`listed in §7.5.1. (Both Matlab and Octave have compatible utilities

`freqz`, which serve the same purpose.) Note that the sampling rate is set to 1, and the frequency axis goes from 0 Hz all the way to the sampling rate, which is appropriate for complex filters (as we will soon see). Since real filters have

*Hermitian*frequency responses (

*i.e.*, an

*even*amplitude response and

*odd*phase response), they may be plotted from 0 Hz to half the sampling rate without loss of information.

Figure 3.15 shows the impulse response of the *complex*
one-pole section

The complex-conjugate section,

Figure 3.19 shows the impulse response of the complex one-pole section

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Sample-Level Implementation in Matlab