firlpnorm (Digital Filter Design Toolkit, MathScript Function)
Owning Class: singlerate
Syntax
b = firlpnorm(n, f, e, mag)
b = firlpnorm(n, f, e, mag, w)
b = firlpnorm(n, f, e, mag, w, p)
[b, err] = firlpnorm(n, f, e, mag)
[b, err] = firlpnorm(n, f, e, mag, w)
[b, err] = firlpnorm(n, f, e, mag, w, p)
Description
Designs a finite impulse response (FIR) filter that uses the least p-th norm algorithm to approximate the frequency response you specify.
Inputs
| Name | Description |
| n | Specifies the order of the filter. n is a nonnegative integer. |
| f | Specifies the frequency points. f is a vector whose values increase monotonically between 0 and 1. |
| e | Specifies the band edge frequencies. e is a vector whose values must also exist in f. |
| mag | Specifies the magnitude response of the filter at f. mag is a vector of the same length as f. |
| w | Specifies the weight of each frequency point. w is a vector of the same length as f. The default is a vector in which each element has a value of 1. |
| p | Specifies the value of p to use in the least p-th norm algorithm. p is a positive integer that must fall in the range [1, 128]. The default is 128. |
Outputs
| Name | Description |
| b | Returns the coefficients of the designed FIR filter. b is a real vector with a length of n+1. |
| err | Returns the least p-th norm approximation error. err is a real number. |
Examples
b = firlpnorm(40, [0, 0.2, 0.5, 0.6, 1], [0, 0.5, 0.6, 1], [1, 2, 1, 0, 0]);fft_mag = abs(fft(b, 16384));
figure;
plot(0:1/8192:1, fft_mag(1:8193));
b = firlpnorm(22, [0, 0.4, 0.6, 1], [0, 0.4, 0.6, 1], [1, 1, 0, 0], [1, 1, 1, 1], 2);
figure;
freqz(b);
b = firlpnorm(22, [0, 0.4, 0.6, 1], [0, 0.4, 0.6, 1], [1, 1, 0, 0], [1, 1, 1, 1], 4);
figure;
freqz(b);