`stepinfo` — Compute step-response metrics from SISO models or sampled responses.

stepinfo(sys) simulates the step response for a supported SISO tf model and returns response metrics. stepinfo(y, t, yfinal) computes metrics from sampled response data.

Syntax

info = stepinfo(sys)
info = stepinfo(y, t)
info = stepinfo(y, t, yfinal)

Inputs

Name	Type	Required	Default	Description
`sys`	`Any`	Yes	—	SISO tf model.
`y`	`NumericArray`	Yes	—	Response samples.
`t`	`NumericArray`	No	—	Time samples.
`yfinal`	`NumericScalar`	No	—	Steady-state value.

Returns

Name	Type	Description
`info`	`Any`	Step-response metrics struct.

Errors

Identifier	When	Message
`RunMat:stepinfo:InvalidArgument`	Inputs do not match supported stepinfo invocation forms.	`stepinfo: invalid argument`
`RunMat:stepinfo:InvalidData`	Response, time, or final-value data is malformed.	`stepinfo: invalid response data`
`RunMat:stepinfo:InvalidSystem`	System input is not a supported SISO tf object.	`stepinfo: invalid system`
`RunMat:stepinfo:UnsupportedModel`	System model form is unsupported.	`stepinfo: unsupported model`
`RunMat:stepinfo:Internal`	Response simulation or metric assembly failed.	`stepinfo: internal error`

How `stepinfo` works

Supports stepinfo(sys) for SISO tf models supported by step.
Supports sampled forms stepinfo(y), stepinfo(y, t), and stepinfo(y, t, yfinal).
Returns a struct with RiseTime, TransientTime, SettlingTime, SettlingMin, SettlingMax, Overshoot, Undershoot, Peak, PeakTime, and SteadyStateValue.
Uses a default settling-time threshold of 2%.
Accepts the name-value option 'SettlingTimeThreshold' with a scalar value between 0 and 1.
Rise-time crossings are linearly interpolated between adjacent samples.

GPU memory and residency

stepinfo returns a host struct.

Examples

Metrics from a transfer function

s = tf('s');
T = feedback(2/(s + 1), 1);
info = stepinfo(T);
info.Overshoot

Expected output:

ans = 0

Metrics from sampled data

t = 0:0.1:5;
y = 1 - exp(-t);
info = stepinfo(y, t, 1);
info.SteadyStateValue

Expected output:

ans = 1

How RunMat validates `stepinfo`

stepinfo validates system inputs, sampled data shape, finite values, time ordering, final value, and settling-threshold options. Tests cover sampled metrics, system metrics through step and dcgain, and VM control workflows.

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

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

Using `stepinfo` with coding agents

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

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

FAQ

Does stepinfo require a transfer-function model?⌄

No. It can also operate on sampled response vectors.

Are the metrics exact analytical values?⌄

For model inputs, metrics are computed from the sampled step response. Crossings are linearly interpolated from those samples.

db · dcgain · feedback · impulse · isstable · nyquist · pole · ss · step · tf

Open-source implementation

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

View the source for stepinfo 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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stepinfo — Compute step-response metrics from SISO models or sampled responses.