`damp` — Return natural frequencies, damping ratios, and poles for control models.

damp(sys) analyzes supported control models by deriving natural frequencies and damping ratios from their poles.

Syntax

wn = damp(sys)
[wn, zeta] = damp(sys)
[wn, zeta, p] = damp(sys)

Inputs

Name	Type	Required	Default	Description
`sys`	`Any`	Yes	—	SISO tf model or ss state-space model.

Returns

Name	Type	Description
`wn`	`NumericArray`	Natural frequencies as an N-by-1 column vector.
`zeta`	`NumericArray`	Damping ratios as an N-by-1 column vector.
`p`	`Any`	Model poles as an N-by-1 real or complex column vector.

Returned values from damp depend on how many outputs the caller requests.

Errors

Identifier	When	Message
`RunMat:damp:InvalidModel`	Input system is malformed or missing model metadata.	`damp: invalid model`
`RunMat:damp:UnsupportedModel`	Model class is unsupported.	`damp: unsupported model`
`RunMat:damp:OutputCount`	More than three outputs are requested.	`damp: too many output arguments`
`RunMat:damp:Internal`	Pole extraction or output construction failed.	`damp: internal error`

How `damp` works

Supports SISO tf objects and ss state-space objects.
Returns wn and zeta as N x 1 real column vectors.
Returns poles as an N x 1 real vector when all poles are real, or an N x 1 complex vector when any pole has a nonzero imaginary part.
For continuous-time models, wn = abs(p) and zeta = -real(p) / wn.
For discrete-time models, damping metrics use the equivalent continuous pole log(p) / Ts, while the p output preserves the original discrete pole.
Static-gain transfer functions return empty column vectors.

GPU memory and residency

damp returns host-resident vectors.

Example

Second-order transfer function

G = tf(1, [100 50 400]);
[wn, zeta, p] = damp(G)

Expected output:

wn contains values near 2, zeta contains values near 0.125, and p contains the complex pole pair.

How RunMat validates `damp`

damp validates model metadata, extracts poles from transfer-function denominators or state-space state matrices, and materializes MATLAB-style column outputs. Tests cover continuous and discrete transfer functions, state-space models, output counts, and descriptor metadata.

Implementation: `crates/runmat-runtime/src/builtins/control/damp.rs`

See Correctness & Trust for the full methodology and coverage table.

Using `damp` with coding agents

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

Run a small damp example, explain the result, then change one input and compare the output.

FAQ

Does damp cancel pole-zero pairs?⌄

No. For tf objects it analyzes the stored denominator polynomial.

Does damp support discrete-time systems?⌄

Yes. Natural frequency and damping ratio are computed from log(p) / Ts; the returned poles remain in the discrete domain.

db · dcgain · feedback · impulse · isstable · nyquist · pole · rlocus · ss · step · stepinfo · tf · zero

Open-source implementation

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

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

About RunMat

RunMat is an open-source runtime that executes MATLAB-syntax code blazing on any GPU. It is licensed under the Apache 2.0 license.

RunMat automatically optimizes your math for GPU execution on Apple, Nvidia, and AMD hardware. No code changes needed. Simulations that took hours now take minutes.
Start running code in seconds. RunMat runs in the browser, on the desktop, or from the CLI. No license server, no IT ticket.

Getting started · Benchmarks · Pricing

damp — Return natural frequencies, damping ratios, and poles for control models.