sinc — Compute the normalized sinc function sin(pi*x)/(pi*x) element-wise.

y = sinc(x) evaluates the normalized sinc function using MATLAB's definition sin(pi*x)/(pi*x), with the removable singularity handled as sinc(0) = 1.

Syntax

Y = sinc(X)

Inputs

Returns

Errors

How sinc works

• Accepts real or complex scalars, vectors, matrices, and N-D tensors.
• Preserves the input shape for vector, matrix, and N-D tensor inputs.
• Returns 1 for exactly zero real inputs.
• Returns exact 0 for finite nonzero integer-valued real inputs, matching MATLAB's sinpi-style integer accuracy where practical.
• Logical and integer inputs are promoted to double precision before evaluation.
• Complex inputs use the analytic extension sin(pi*z)/(pi*z) and return 1 + 0i for z == 0.
• GPU inputs stay resident when the active provider supports unary_sinc; otherwise RunMat gathers automatically and evaluates with the host implementation.

Does RunMat run sinc on the GPU?

Provider-backed execution uses the same normalized sinc semantics, including sinc(0) == 1 and exact zeros for finite nonzero integer-valued real inputs.

If the provider declines the operation, RunMat gathers through the active provider and evaluates with the host implementation.

Fusion emits a guarded normalized sinc expression with explicit zero and integer branches for real elementwise graphs.

GPU memory and residency

sinc keeps real GPU tensors resident when the active provider exposes unary_sinc. The runtime preserves a host fallback for providers that do not support the hook.

Examples

Evaluate sinc at zero

y = sinc(0)

Expected output:

y = 1

Evaluate sinc at integer inputs

x = 1:5;
y = sinc(x)

Expected output:

y = [0 0 0 0 0]

Evaluate normalized sinc values

x = [-1 0 1 0.5];
y = sinc(x)

Expected output:

y = [0 1 0 0.6366]

Preserve matrix shape

A = [0 0.5; 1.5 2];
Y = sinc(A)

Expected output:

Y =
    1.0000    0.6366
   -0.2122         0

Evaluate sinc for a complex value

z = sinc(0.5 + 0.25i)

Use gpuArray input

g = gpuArray([0 0.5 1]);
y = sinc(g);
result = gather(y)

Expected output:

result = [1 0.6366 0]

Using sinc with coding agents

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

FAQ

Related Math functions

Open-source implementation

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

• View the source for sinc 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.

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