You are here : matlabSignal Processingmaxflat

maxflat() - Signal Processing

```[b,a] = maxflat(n,m,Wn) is a lowpass Butterworth
filter with numerator and denominator coefficients b and a of
orders n and m, respectively. Wn is
the normalized cutoff frequency at which the magnitude response of
the filter is equal to 1/2 (approximately
–3 dB). Wn must be between
0 and 1, where 1 corresponds to the Nyquist frequency.b = maxflat(n,'sym',Wn) is
a symmetric FIR Butterworth filter. n must be even,
and Wn is restricted to a subinterval of [0,1].
The function raises an error if Wn is specified
outside of this subinterval.[b,a,b1,b2] = maxflat(n,m,Wn) returns two polynomials b1 and b2 whose
product is equal to the numerator polynomial b (that
is, b = conv(b1,b2)). b1 contains all the zeros at z = -1, and b2 contains
all the other zeros.[b,a,b1,b2,sos,g] = maxflat(n,m,Wn) returns the second-order
sections representation of the filter as the filter matrix sos and
the gain g.[...] = maxflat(n,m,Wn,'design_flag') enables
you to monitor the filter design, where 'design_flag' is'trace' for a textual display of
the design table used in the design'plots' for plots of the filter's
magnitude, group delay, and zeros and poles'both' for both the textual display
and plots```

Syntax

`[b,a] = maxflat(n,m,Wn)b = maxflat(n,'sym',Wn)[b,a,b1,b2] = maxflat(n,m,Wn)[b,a,b1,b2,sos,g] = maxflat(n,m,Wn)[...] = maxflat(n,m,Wn,'design_flag')`

Example

```Generalized Butterworth FilterOpen This Example
Design a generalized Butterworth filter with normalized cutoff frequency
rad/s. Specify a numerator order of 10 and a denominator order of 2. Visualize the frequency response of the filter.
n = 10;
m = 2;
Wn = 0.2;

[b,a] = maxflat(n,m,Wn);
fvtool(b,a)```