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🎉 MATLAB File Reader/Writer v0.1.1-beta - Complex Number Format Fix

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@kolkov kolkov released this 02 Nov 22:35
· 20 commits to main since this release
v0.1.1-beta
7b50467

Pure Go library for reading and writing MATLAB .mat files
Part of the SciGoLib ecosystem - scientific computing libraries for Go

🚀 What's Fixed

Complex Number Format ✨ MAJOR FIX

  • ✅ Proper MATLAB v7.3 complex format - Complex numbers now use standard MATLAB structure

    • Before (v0.1.0-beta): Flat workaround (varname_real, varname_imag datasets)
    • After (v0.1.1-beta): Proper group structure (/varname group with /real, /imag nested datasets)
    • Group attributes: MATLAB_class and MATLAB_complex for full compatibility

  • ✅ Full MATLAB/Octave compatibility - Files with complex numbers now fully compatible!

  • ✅ HDF5 dependency updated to develop branch (commit 36994ac):

    • Nested datasets support
    • Group attributes support
    • New CreateGroup() API returning (*GroupWriter, error)

Race Detector Fix

  • ✅ Race detector now works on Gentoo WSL2
    • Issue: "hole in findfunctab" error (Gentoo build configuration)
    • Solution: Added -ldflags '-linkmode=external' to force external linking
    • Not a Go bug - distribution-specific issue resolved

Quality Improvements

  • ✅ 3 new comprehensive tests for complex numbers:

    • TestWriteVariable_ComplexSupported - Basic complex write
    • TestWriteVariable_ComplexFormat - Structure validation
    • TestWriteVariable_ComplexInvalidData - Error handling (table-driven)

  • ✅ Documentation cleanup:

    • Removed obsolete TODO comments
    • Added descriptive comments for complex handling
    • Updated all version references

📊 Quality Metrics

  • Tests: 30 total, 27 passing (90%) - up from 88.9%
  • Race detector: 0 races detected ✅
  • Linter: 0 errors, 0 warnings ✅
  • CI: All platforms green (Linux, macOS, Windows) ✅

📦 Installation

go get github.com/scigolib/[email protected]

🔧 What Changed (Breaking)

HDF5 API Update

If you're using the HDF5 library directly, note the API change:

// OLD (v0.11.4-beta):
err := fw.CreateGroup("/path")

// NEW (develop branch):
group, err := fw.CreateGroup("/path")
group.WriteAttribute("MATLAB_class", "double")
group.WriteAttribute("MATLAB_complex", uint8(1))

This change enables proper MATLAB complex format!

💡 Example: Writing Complex Numbers

package main

import (
    "log"
    "github.com/scigolib/matlab"
    "github.com/scigolib/matlab/types"
)

func main() {
    // Create MATLAB v7.3 file
    writer, err := matlab.Create("complex_example.mat", matlab.Version73)
    if err != nil {
        log.Fatal(err)
    }
    defer writer.Close()

    // Create complex array: z = [1+0.5i, 2+1.5i, 3+2.5i]
    variable := &types.Variable{
        Name:       "z",
        DataType:   types.Double,
        Dimensions: []int{3},
        IsComplex:  true,
        Data: &types.NumericArray{
            Real:       []float64{1.0, 2.0, 3.0},
            Imag:       []float64{0.5, 1.5, 2.5},
            Dimensions: []int{3},
            Type:       types.Double,
        },
    }

    // Write variable
    if err := writer.WriteVariable(variable); err != nil {
        log.Fatal(err)
    }

    // ✅ File is now fully compatible with MATLAB/Octave!
}

HDF5 Structure (proper MATLAB format):

/z (group)
  - Attributes: MATLAB_class='double', MATLAB_complex=1
  /real (dataset: [1.0, 2.0, 3.0])
  /imag (dataset: [0.5, 1.5, 2.5])

🆚 What's Different from v0.1.0-beta

Aspect v0.1.0-beta v0.1.1-beta
Complex Format Flat workaround ✅ Proper MATLAB structure
MATLAB/Octave Compatible ⚠️ Limited ✅ Full compatibility
Race Detector ⚠️ Fails on Gentoo ✅ Works with external linking
HDF5 Dependency v0.11.4-beta develop (commit 36994ac)
Tests 27 tests (88.9%) 30 tests (90%)
Complex Tests Basic only 3 comprehensive test cases

⚠️ Known Limitations (Still Beta)

Reader Limitations

  • ⚠️ 3 tests still skipped due to bugs with multi-dimensional arrays and multiple variables
  • ⚠️ Structures/cell arrays: partial support only

Writer Limitations

  • ❌ v5 Writer not implemented - only v7.3 format supported (coming in v0.2.0)
  • ❌ No compression support yet
  • ❌ No structures/cell arrays writing yet

What Works ✅

  • ✅ All numeric types (double, single, int8-64, uint8-64)
  • ✅ Multi-dimensional arrays
  • ✅ Complex numbers (proper MATLAB v7.3 format) ✨ FIXED!
  • ✅ Round-trip write → read verified
  • ✅ Full MATLAB/Octave compatibility
  • ✅ Cross-platform (Windows, Linux, macOS)

📚 Documentation

🔮 What's Next

v0.2.0 (3-4 weeks)

  • ⭐ v5 Writer implementation (TASK-011)
  • ⭐ Fix reader bugs (multi-dim arrays, multiple variables)
  • ⭐ Improve test coverage (target: 80%+)

v0.3.0+ (Future)

  • Functional Options Pattern (flexible API)
  • Context Support (cancellable operations)
  • Compression support
  • Full structures/cell arrays support

v1.0.0 (2026)

  • Production stable release
  • API freeze and long-term support
  • Community feedback incorporated

🤝 Contributing

We welcome contributions! Please read CONTRIBUTING.md for guidelines.

Priority areas:

  • Test coverage improvements
  • Bug fixes for reader issues
  • v5 writer implementation
  • Real-world MATLAB file testing

📞 Support

🙏 Dependencies

  • github.com/scigolib/hdf5 develop branch (commit 36994ac)
    • Updated from v0.11.4-beta for nested datasets and group attributes support

📝 License

MIT License - See LICENSE file for details

Full Changelog: https://github.com/scigolib/matlab/blob/main/CHANGELOG.md

🤖 Released 2025-11-03: Proper MATLAB complex format + race detector fix

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