colormap — Set the active colormap in MATLAB and RunMat plotting.
colormap sets the active color palette for the current plotting context. It accepts a named palette or an m-by-3 RGB matrix with values in [0, 1], and affects colormap-driven visualizations such as imagesc, surf, and contourf, scoped to the active axes in MATLAB and RunMat.
Syntax
ok = colormap(name)
ok = colormap(map)Inputs
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
name | StringScalar | Yes | — | Colormap name. |
map | NumericArray | Yes | — | m-by-3 RGB colormap array with values in [0, 1]. |
Returns
| Name | Type | Description |
|---|---|---|
ok | LogicalArray | True on successful colormap update. |
Errors
| Identifier | When | Message |
|---|---|---|
RunMat:colormap:InvalidArgument | Colormap input is missing, unknown, or not a valid m-by-3 RGB array. | colormap: invalid argument |
How colormap works
- Supported colormap names include
parula,colorcube,viridis,plasma,inferno,magma,turbo,jet,hot,cool,spring,summer,autumn,winter,gray,bone,copper,pink, andlines. - Named colormaps are also available as RGB array generator functions, so MATLAB forms such as
colormap(jet),colormap(gray(64)), andc = turbo(128)are supported. - RGB matrix inputs are validated as m-by-3 numeric arrays with finite values in [0, 1] and are preserved in plotting state and scene serialization.
- Unknown colormap names raise errors rather than silently falling back.
- Colormap state composes naturally with
colorbar,imagesc,surf, and filled contour plots. - Colormap changes apply to the current axes context in the plotting state model.
Examples
Apply a palette to a scaled image
[X, Y] = meshgrid(linspace(-3, 3, 60), linspace(-3, 3, 60));
A = sin(X) .* cos(Y);
imagesc(A);
colormap('jet');
colorbar;Compare palettes across subplots
[X, Y] = meshgrid(linspace(-3, 3, 40), linspace(-3, 3, 40));
Z = sin(X) .* cos(Y);
subplot(1, 2, 1);
surf(X, Y, Z);
colormap('parula');
subplot(1, 2, 2);
contourf(X, Y, Z);
colormap('turbo');Apply a generated RGB colormap matrix
surf(peaks(40));
colormap(parula(128));
colorbar;Apply a MATLAB-style named colormap generator
mandelbrot();
colormap(jet);Using colormap with coding agents
Open a RunMat example with live inputs, then ask the agent to explain how colormap changes the result.
Run a small colormap example, explain the result, then change one input and compare the output.
FAQ
What colormaps are available?⌄
RunMat ships with: parula, colorcube, viridis, plasma, inferno, magma, turbo, jet, hot, cool, spring, summer, autumn, winter, gray, bone, copper, pink, and lines. Unknown names raise an error — no silent fallback.
Which colormaps are perceptually uniform?⌄
viridis, plasma, inferno, and magma are designed so that equal steps in data value produce equal perceptual changes in color. Use these for quantitative data where you want the visual contrast to faithfully represent magnitude differences. parula is also a good default. Avoid jet for quantitative work — it introduces false banding.
Can I define a custom colormap?⌄
Yes. Pass an m-by-3 RGB matrix with finite values in [0, 1], for example colormap([0 0 0; 1 0.5 0; 1 1 1]). RunMat preserves matrix inputs in plotting state and scene serialization.
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More plotting resources
Open-source implementation
Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how colormap is executed, line by line, in Rust.
- View the source for colormap 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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