refline — Add a reference line y = m*x + b to the current or specified axes.
refline appends straight reference lines to the current or specified axes and returns the created line handle or handles when requested. With no coefficients it adds least-squares lines for eligible scatter-style series in the axes. With coefficients it draws y = m*x + b over the current x-axis span.
Syntax
refline()
refline(coeffs)
refline(m, b)
refline(___, LineSpec, Name, Value)
refline(ax, ___)
h = refline(___)
h = refline(ax, ___)Inputs
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
coeffs | NumericArray | Yes | — | Two-element vector [slope intercept]. |
m | NumericArray | Yes | — | Line slope. |
b | NumericArray | Yes | — | Line y-intercept. |
style | Any | Variadic | — | Optional LineSpec or line Name/Value pairs. |
ax | AxesHandle | Yes | — | Target axes handle. |
Returns
| Name | Type | Description |
|---|---|---|
h | NumericArray | Line graphics handle. |
Errors
| Identifier | When | Message |
|---|---|---|
RunMat:refline:InvalidArgument | Axes handle, coefficient inputs, or style options are malformed. | refline: invalid argument |
RunMat:refline:Internal | RunMat cannot construct or register the reference line. | refline: internal error |
How refline works
refline()andrefline(ax)add least-squares reference lines for scatter-style series in the current or specified axes, matching MATLAB'slsline-style behavior.refline([m b])andrefline(m,b)draw a line with slopemand interceptb; the compatibility target documents single and double coefficients, while RunMat mode additionally accepts all eight typed-integer classes after exact binary64 representability checks and retains logical coefficients as a separately declared extension.refline(ax,...)targets the supplied axes handle.- The line uses explicit
XLimwhen present. If x-limits are automatic, RunMat derives a finite x span from the target axes' visible data bounds and falls back to[0,1]only when no finite span is available. - As a RunMat extension, optional LineSpec and line Name/Value pairs such as
Color,LineStyle,LineWidth, andDisplayNameare accepted using the same parser as line plotting builtins. - The return value is a line graphics handle compatible with
getandsetfor line properties such asXData,YData,Color,LineStyle,LineWidth, andDisplayName.
Examples
Add a least-squares reference line to a scatter plot
scatter(x, y);
h = refline;Add a line with slope and intercept
h = refline(2, 1);Use coefficient vector form and style the line
h = refline([0.5 3], '--r', 'DisplayName', 'reference');Target a specific axes
ax = subplot(1,2,2);
refline(ax, [1 0]);Using refline with coding agents
Open a RunMat example with live inputs, then ask the agent to explain how refline changes the result.
Run a small refline example, explain the result, then change one input and compare the output.
FAQ
Does refline compute a least-squares fit?⌄
Yes, when called without explicit coefficients it adds least-squares lines for eligible scatter-style series in the axes. When coefficients are supplied, it draws exactly y = m*x + b and does not fit a model.
Related Stats functions
Summary
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Ml
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Random
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Hist
Open-source implementation
Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how refline is executed, line by line, in Rust.
- View the source for refline 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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