[Feature] Add Colville test function (closes #12)

[Jitenndra03]

Description

Adds the Colville benchmark function to the algebraic test functions in Surfaces.
The Colville function is a 4-dimensional nonlinear optimization benchmark with a global minimum at (1, 1, 1, 1).

This implementation includes:

• Scalar objective evaluation
• Vectorized batch evaluation
• Search space generation
• Metadata (formula, bounds, reference)

Reference:
https://www.sfu.ca/~ssurjano/colville.html

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Related Issues

Fixes #12

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Type of Change

• [BUG] - Bug fix (non-breaking change fixing an issue)
• [ENH] - New feature (non-breaking change adding functionality)
• [DOC] - Documentation only
• [MNT] - Maintenance (refactoring, dependencies, CI)

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How was this solved?

Implemented a new algebraic test function class ColvilleFunction that inherits from AlgebraicFunction.

Key steps:

• Implemented the Colville function formula in _objective
• Added vectorized evaluation using _batch_objective
• Defined metadata such as bounds, formula, reference, and global optimum
• Implemented _search_space using existing helper utilities
• Fixed dimensionality to 4 variables

The implementation follows the structure and conventions used in other algebraic test functions in the repository.

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Checklist

Required

• PR title includes appropriate tag: [BUG], [ENH], [DOC] or [MNT]
• Code passes make check (lint, format, isort)

Tests

• Tests added/updated for changes
• No tests needed (briefly explain why: Function follows existing algebraic function patterns and was verified through manual evaluation)

Documentation

• Documentation added/updated (docstrings and metadata fields)
• No documentation needed

Note: New features ([ENH]) typically require both tests and documentation.

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Testing

The function was tested manually.

Example:

from surfaces.test_functions.algebraic import ColvilleFunction

f = ColvilleFunction()

print(f({"x0":1,"x1":1,"x2":1,"x3":1}))

Output:

0.0

This matches the known global minimum:

f(1,1,1,1) = 0

[SimonBlanke]

check the code quality

[Jitenndra03]

Hi @SimonBlanke,

Sorry, but I couldn't understand the requested changes. Could you please clarify what needs to be modified?

[SimonBlanke]

Hi @SimonBlanke,

Sorry, but I couldn't understand the requested changes. Could you please clarify what needs to be modified?

It was about this code-quality check in the CI:
https://github.com/SimonBlanke/Surfaces/actions/runs/22917946441/job/66622118162?pr=18

But you took care of it. Well done.

Let's see how the rest of the tests go.

[Jitenndra03]

Hi @SimonBlanke,

I ran the full integration test suite in a Python 3.11 environment
(using GitHub Codespaces) and all tests pass successfully.

Please let me know if any further changes are required.

[SimonBlanke]

Hi @SimonBlanke,

I ran the full integration test suite in a Python 3.11 environment (using GitHub Codespaces) and all tests pass successfully.

Please let me know if any further changes are required.

This was just a sporadic test fail.

[SimonBlanke]

Great work. You understood the structure of the module and the test-functions architecture.