fvtool

Builtin index · Signal processing

fvtool(filt, [n=512])

Input: filt, n · Output: no output

What it is

filt: a Model (kind "filter"); n (optional number, default 512). MATLAB's Filter Visualization Tool: a 2x2 figure (magnitude response in dB, phase, group delay, impulse response) built from freqz/group_delay/sosfilt. Callable as filt.fvtool().

Overloads

One call shape — this function is not overloaded.

Examples

From the documentation, and run by the build -- the output and the figure below are what the engine actually produced. Simplest first.

fs = 1000
ep = ellip(4, 1, 40, "low", 100, fs)
c1 = cheby1(4, 1, "low", 100, fs)
c2 = cheby2(4, 40, "low", 100, fs)
print("ellip stable: {is_stable(ep)}, cheby1 stable: {is_stable(c1)}, cheby2 stable: {is_stable(c2)}")

fir = fir1(6, 100, kind="low", window="hamming", fs=fs)
b = fir.b
a = [1]
n = 0:1:255
t = n / fs
x = sin(2*pi*40*t) + sin(2*pi*300*t)
y  = filter_ba(b, a, x)
y2 = lfilter(b, a, x)               # lfilter is the same builtin under another name

print("filter_ba/lfilter agree: {max(abs(y - y2)) < 1e-12}")

lsq = firls(20, [0, 0.2, 0.3, 1.0], [1, 1, 0, 0])   # low-pass band edges/response

print("firls taps: {length(lsq.b)}")

gd = group_delay(fir, 256)
print("FIR group delay (should be ~order/2=3): {gd[10]}")
print("ellip filter has {length(poles(ep))} poles")

ep.fvtool()   # 2x2 magnitude/phase/group-delay/impulse-response figure

pzplot(ep)    # pole-zero plot with the unit circle and stability verdict

ellip stable: true, cheby1 stable: true, cheby2 stable: true
filter_ba/lfilter agree: true
firls taps: 21
FIR group delay (should be ~order/2=3): 3
ellip filter has 4 poles

from signal-processing

How it works

fvtool(filt, [n=512]) — MATLAB's own name (Filter Visualization Tool): a 2x2 diagnostic figure (magnitude/"gain" response in dB, phase, group delay, impulse response) built entirely from freqz/group_delay/sosfilt plus the existing panel(rows, cols, index) grid layout — no new rendering primitives needed. Callable as filt.fvtool() via the ordinary recv.method(args) sugar, same as any other function taking a model as its first argument.

From the note above this builtin in the interpreter, where the reasoning was written down as it was built.