These four functions can be combine

These four functions can be combined into one function, called
ampl-res, that can be written to determine the type of the linear-phase
filter and to implement the appropriate amplitude response expression.
This is explored in Problem P7.6. The use of these functions is described
in Examples 7.4 through 7.7.
The zerophase function from the SP toolbox is similar in use to the
freqz function. The invocation [Hr,w, phi] = zerophase(b,a) returns
the amplitude response in Hr, evaluated at 512 values around the top half
of the unit circle in the array w and the continuous phase response in
phi. Thus, this function can be used for both FIR and IIR filters. Other
invocations are also available

Kết quả (Anh) 3:

这四个函数可以组合成一个函数，称为大量的水库，可以书面确定的线性相位的类型滤波器，并实现适当的振幅响应表达式。这是p7.6问题探讨。使用这些功能的描述在7.4到7.7的例子中。从SP工具箱的零相位函数是使用类似freqz函数。调用[φ]，W =零（B，A）返回在人力资源的振幅响应，评估在512个值周围的上半数组中的单位圆的W和连续相位响应披。因此，此功能可用于FIR和IIR滤波器。其他调用也可