interp1 — Interpolate one-dimensional sampled data in MATLAB and RunMat.

interp1(x, y, xq) estimates values of one-dimensional sampled data at query points xq. Default interpolation is linear, with additional methods such as nearest, spline, and pchip following MATLAB semantics.

Syntax

Vq = interp1(Y, Xq)
Vq = interp1(X, Y, Xq)
Vq = interp1(Y, Xq, method)
Vq = interp1(X, Y, Xq, method)
Vq = interp1(Y, Xq, extrap)
Vq = interp1(X, Y, Xq, extrap)
Vq = interp1(Y, Xq, method, extrap)
Vq = interp1(X, Y, Xq, method, extrap)

Inputs

Returns

Errors

How interp1 works

• interp1(y, xq) uses implicit sample points 1:numel(y).
• interp1(x, y, xq, method) supports linear, nearest, spline, and pchip.
• Out-of-range query points return NaN unless an extrapolation value or 'extrap' is supplied.
• Dense real numeric arrays are supported. Real gpuArray Y/query inputs stay resident for linear and nearest interpolation when X is implicit or host-validated.

GPU memory and residency

interp1 uploads implicit or host-validated sample points, evaluates linear/nearest queries with provider interp1, and returns a resident gpuArray output. Spline, pchip, complex, and resident-X validation paths use the host implementation until dedicated validation/interpolation kernels cover those cases.

Examples

Linear interpolation

x = [1 2 3];
y = [10 20 40];
yq = interp1(x, y, [1.5 2.5])

Expected output:

yq = [15 30]

Spline interpolation

x = [1 2 3];
y = [1 4 9];
yq = interp1(x, y, [1.5 2.5], 'spline')

Expected output:

yq = [2.25 6.25]

Resident GPU linear interpolation

Y = gpuArray([10 20 40]);
Vq = interp1(Y, gpuArray([1.5 2.5]))

Expected output:

Vq = gpuArray([15 30])

Using interp1 with coding agents

Open a RunMat example with live inputs, then ask the agent to explain how interp1 changes the result.

Related Math functions

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how interp1 is executed, line by line, in Rust.

• View the source for interp1 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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