COMSOL binary mesh (.mphbin)

The binary twin of the COMSOL text mesh: the same objects, element types, node order, entity indices and Selections, serialised in binary.

Format name	mphbin
Extensions	.mphbin
Read / Write	✓ / ✓
Extra dependencies	—

Reading & writing

import meshioplusplus

mesh = meshioplusplus.read("model.mphbin")
meshioplusplus.mphbin.write("out.mphbin", mesh)

Encoding

• Integers are little-endian int32 and doubles little-endian float64.
• A string is an int32 length followed by one int32 code point per character.
• A file opens with the int32 values 0 1 (the version), then the tag count, which is how sniff_format recognises it.

Everything else — objects, Mesh versions, Selections, node order, what the writer derives — is described on the mphtxt page.

The binary layout follows COMSOL's binary file format and AWS Palace's reader. No public COMSOL-written .mphbin file was found to test against; the fixture tests/python/meshes/comsol/two_domains.mphbin is written by tools/gen_comsol_fixtures.py, which encodes the same values as two_domains.mphtxt independently of meshio++.

Quirks & limitations

• No provenance. The format has no comment, so none is written. The writer still consults the provenance machinery, so Mode.REQUIRED raises there, as for the other formats without a slot.
• 32-bit values. Values beyond 32 bits cannot be written.