RunMat
  • Pricing
RunMat
GitHub
GitHub
DownloadSign InTry in Browser
DesktopRuntimeServer
RunMat

Run math blazing fast

GitHubX (Twitter)LinkedIn

Company

  • About
  • Pricing
  • Contact
  • License
  • Privacy

Learn

  • Docs
  • Blog
  • Benchmarks
  • RunMat vs MATLAB Online

Get product updates and release notes from the RunMat team.

© 2026 Dystr · Made withfor the scientific community.

RunMat™ is a registered trademark of Dystr, Inc. MATLAB® is a registered trademark of The MathWorks, Inc. RunMat is not affiliated with, endorsed by, or sponsored by The MathWorks, Inc.

/
See all docs
Builtin Reference
    • fea.boundaryCondition
    • fea.compare
    • fea.domain
    • fea.field
    • fea.interface
    • fea.loadCase
    • fea.material
    • fea.materialAssignment
    • fea.model
    • fea.plan
    • fea.plot
    • fea.results
    • fea.run
    • fea.runOptions
    • fea.step
    • fea.study
    • fea.sweep
    • fea.trends
    • fea.validate

fea.interface — Create a typed RunMat FEA interface.

fea.interface(id, primaryRegion, secondaryRegion, Name, Value, ...) creates contact, fluid-structure, or conjugate heat-transfer interface data.

Syntax

interface = fea.interface(id, primaryRegion, secondaryRegion, Name, Value, ...)

Inputs

NameTypeRequiredDefaultDescription
idStringScalarYes—Interface id.
primaryRegionStringScalarYes—Primary geometry region selector.
secondaryRegionStringScalarYes—Secondary geometry region selector.
Name, ValueAnyVariadic—Interface kind and numeric fields.

Returns

NameTypeDescription
resultAnyFEA object or operation result.

Errors

IdentifierWhenMessage
RunMat:fea:LoadFailedA .fea document cannot be read, parsed, or resolved.fea: failed to load FEA document
RunMat:fea:InvalidInputA builtin receives an unsupported argument pattern or object type.fea: invalid input
RunMat:fea:OperationFailedA validation, planning, run, result-query, comparison, or trend operation fails.fea: operation failed
RunMat:fea:InternalAn FEA object or operation result cannot be converted to a RunMat value.fea: internal error

How fea.interface works

  • Interface id and both region selectors are exact text values; Kind defaults to contact.
  • Finite real numeric fields accept all eight built-in integer classes and cross one host-only binary64 model-storage boundary after field and shape validation.
  • Contact fields are penalty stiffness scale, maximum penetration ratio, and friction coefficient; FSI fields are normal stiffness, damping ratio, and relaxation factor; CHT fields are thermal conductance, contact resistance, and relaxation factor.
  • Unknown fields, nonfinite values, nonscalar values, and resident numeric fields are rejected before object construction.

Example

Create a contact interface

contact = fea.interface("joint", "face:a", "face:b", "Kind", "contact", "FrictionCoefficient", uint8(0));

Using fea.interface with coding agents

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

Run a small fea.interface example, explain the result, then change one input and compare the output.

FAQ

Does interface construction use the GPU?⌄

No. It creates host model data; backend execution occurs only in a later solve.

Related Fea functions

fea.boundaryCondition · fea.compare · fea.domain · fea.field · fea.loadCase · fea.material · fea.materialAssignment · fea.model · fea.plan · fea.plot · fea.results · fea.run · fea.runOptions · fea.step · fea.study · fea.sweep · fea.trends · fea.validate

Open-source implementation

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

  • View the source for fea.interface 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.
  • Start running code in seconds. RunMat runs in the browser, on the desktop, or from the CLI. No license server, no IT ticket.

Getting started · Benchmarks · Pricing

Download RunMat

Download RunMat for full performance, or use RunMat in your browser for zero setup.

Download RunMatOpen Sandbox
On this page
  • Syntax
  • Inputs
  • Returns
  • Errors
  • How fea.interface works
  • Example
  • Create a contact interface
  • Using fea.interface with coding agents
  • FAQ
  • Related Fea functions
  • Open-source implementation
  • About RunMat