ppval — Evaluate piecewise-polynomial structures in MATLAB and RunMat.
ppval(pp, xq) evaluates piecewise-polynomial structure pp at query points xq. Breakpoint selection and output-shape behavior follow MATLAB semantics.
Syntax
Vq = ppval(pp, Xq)Inputs
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
pp | Any | Yes | — | Piecewise-polynomial struct with form/breaks/coefs fields. |
Xq | Any | Yes | — | Query points. |
Returns
| Name | Type | Description |
|---|---|---|
Vq | NumericArray | Evaluated piecewise-polynomial values at query points. |
Errors
| Identifier | When | Message |
|---|---|---|
RunMat:ppval:InvalidArgument | The piecewise-polynomial struct shape or field grammar is invalid. | ppval: invalid argument |
RunMat:ppval:InvalidInput | Query points or polynomial coefficients are invalid for evaluation. | ppval: invalid input |
RunMat:ppval:Internal | Piecewise-polynomial output assembly fails due to internal tensor construction paths. | ppval: internal interpolation failure |
How ppval works
- Accepts pp structures with
form,breaks,coefs,pieces,order, anddimfields. - Uses Horner evaluation within each interval.
- Extrapolates outside the break range, matching MATLAB pp evaluation behavior.
Example
Evaluate a spline pp structure
pp = spline([1 2 3], [1 4 9]);
yq = ppval(pp, [1.5 2.5])Expected output:
yq = [2.25 6.25]Using ppval with coding agents
Open a RunMat example with live inputs, then ask the agent to explain how ppval changes the result.
Run a small ppval example, explain the result, then change one input and compare the output.
Related Math functions
Elementwise
abs · angle · complex · conj · double · exp · expm1 · factorial · gamma · hypot · imag · ldivide · log · log10 · log1p · log2 · minus · nextpow2 · plus · pow2 · power · rdivide · real · sign · single · sqrt · times
Trigonometry
acos · acosh · asin · asinh · atan · atan2 · atanh · cos · cosd · cosh · deg2rad · rad2deg · sin · sind · sinh · tan · tand · tanh
Reduction
all · any · cummax · cummin · cumprod · cumsum · cumtrapz · diff · gradient · max · mean · median · min · nnz · prod · std · sum · trapz · var
Structure
Open-source implementation
Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how ppval is executed, line by line, in Rust.
- View the source for ppval 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.
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