Orphaned SIMD test double with a dangling include, and a stale README claim

[gabrielfrasantos]

Severity: medium
Domain: math / docs
Status: VERIFIED — read against a210d34 on 2026-08-10
Suggested labels: bug, cleanup, documentation

Summary

SingleInstructionMultipleDataStub.hpp includes a header that no longer exists, so the file cannot
compile if anything includes it. The interface it derives from was removed, but the stub was left
behind. The type name is also misspelled twice. Separately, README.md still advertises SIMD as an
available capability.

Location

numerical/math/test_doubles/SingleInstructionMultipleDataStub.hpp

Evidence

#pragma once
#include "numerical/math/SingleInstructionMultipleData.hpp"   // no longer exists

namespace math
{
    class SingleInstructionMultipltDataStub                     // "Multiplt"
        : public SingleInstructionMultipltData                  // "Multiplt"
    {
        ...
    };
}

numerical/math/SingleInstructionMultipleData.hpp existed at 87a70dd (2026-08-03) and was
removed afterwards; the stub was not removed with it.

README.md still lists:

| Performance Optimization | Compiler optimizations, SIMD |

Decision required

Either:

• Restore SingleInstructionMultipleData.hpp if the SIMD interface is still intended, fix the
  Multiplt → Multiple spelling, and add a concrete implementation plus a doc page; or
• Delete the stub and remove "SIMD" from the README capability table.

Notes

The stub is presumably not currently referenced by any compiled target (the build would otherwise
fail), which is why this went unnoticed. Confirm with a CMake/grep check before deleting.