freqz — Evaluate digital filter frequency response.

freqz(b, a, n) evaluates the complex frequency response of a digital filter at n points between 0 and Nyquist. With fs, returned frequencies are in Hz instead of radians/sample.

Syntax

freqz(b, a, n)

How freqz works

• Default response length is 512 samples.
• [H, w] = freqz(...) returns complex response H and frequency vector w as column vectors.
• Without fs, w is in radians/sample over [0, pi).
• With fs, w is in Hz over [0, fs/2).

Does RunMat run freqz on the GPU?

Host-side analysis only.

GPU coefficient inputs are gathered before evaluation.

Examples

Evaluate a simple FIR response

[H, w] = freqz([1 1], 1, 4);
fprintf('%.1f %.1f %.4f\n', real(H(1)), imag(H(3)), w(3));

Expected output:

2.0 -1.0 1.5708

Evaluate a response in Hz

b = fir1(20, 0.25);
[H, f] = freqz(b, 1, 8, 1000);
fprintf('%.1f %.1f\n', f(1), f(end));

Expected output:

0.0 437.5

Using freqz with coding agents

Open a RunMat example with live inputs, then ask the agent to explain how freqz changes the result.

FAQ

Related Math functions

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how freqz is executed, line by line, in Rust.

• View the source for freqz in Rust on GitHub
• Learn how the RunMat runtime works
• Found a bug? Open an issue with a minimal reproduction.

About RunMat

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