[Draft] showcase potential simplification of matrix op using concepts

[tdavidcl]

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[github-actions]

Thanks @tdavidcl for opening this PR!

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[gemini-code-assist]

Code Review

This pull request refactors matrix operations to utilize C++20 concepts and simplifies template argument deduction across the library. Feedback suggests moving the newly introduced traits and concepts into the shammath namespace to avoid global scope pollution. Additionally, mdspan parameters should be passed by value, and constraints should be adjusted to allow for implicit type conversions in mat_set_vals and to restore type safety in mat_sub. An aliasing check for source and destination matrices is also recommended.

[gemini-code-assist]

The traits and concepts introduced here are defined in the global namespace. They should be moved inside the shammath namespace to prevent name collisions and maintain a clean global scope, consistent with the rest of the library.

[gemini-code-assist]

mdspan is a lightweight view and should be passed by value. Additionally, the requires clause uses std::same_as, which is overly restrictive as it prevents using functors that return types implicitly convertible to the matrix's value type (e.g., returning an int for a double matrix). Using std::convertible_to is more idiomatic and flexible.

Suggested change

	inline void mat_set_vals(MdspanRank<2> auto &input, Func &&func)
	requires requires(Func f, int a, int b) {
	{ f(a, b) } -> std::same_as<mdspan_value_t<decltype(input)>>;
	}
	inline void mat_set_vals(MdspanRank<2> auto input, Func &&func)
	requires requires(Func f, int a, int b) {
	{ f(a, b) } -> std::convertible_to<mdspan_value_t<decltype(input)>>;
	}

[github-actions]

Workflow report

workflow report corresponding to commit d010790
Commiter email is timothee.davidcleris@proton.me

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Pre-commit check report

Pre-commit check: ✅

trim trailing whitespace.................................................Passed
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Test pipeline can run.

Doxygen diff with main

Removed warnings : 0
New warnings : 5
Warnings count : 8712 → 8717 (0.1%)

Detailed changes :

+ src/shammath/include/shammath/matrix_op.hpp:106: warning: The following parameter of shammath::mat_set_identity(MdspanRank< 2 > auto input) is not documented:
+ src/shammath/include/shammath/matrix_op.hpp:106: warning: argument 'input1' of command @param is not found in the argument list of shammath::mat_set_identity(MdspanRank< 2 > auto input)
+ src/shammath/include/shammath/matrix_op.hpp:35: warning: Member is_mdspan_v (variable) of file matrix_op.hpp is not documented.
+ src/shammath/include/shammath/matrix_op.hpp:44: warning: Member mdspan_value_t (typedef) of file matrix_op.hpp is not documented.