add ordering (argsort) algorithm with caller-provided output#173
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correaa wants to merge 7 commits into
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add ordering (argsort) algorithm with caller-provided output#173correaa wants to merge 7 commits into
correaa wants to merge 7 commits into
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ordering() writes the index permutation that sorts a 1D range without moving the data; output goes into a caller-provided random-access range (no internal allocation). Adds test/ordering.cpp. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
…fers std::sort inlined over a compile-time-sized std::array<,3> trips gcc's -Warray-bounds (introsort's threshold-16 path is dead but flagged at -O3). Use multi::array output buffers (and data_elements() for the pointer case) which gcc cannot bound, so the false positive disappears. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
dst[k] = src[order[k]]; no internal allocation, src untouched. Works for N-dimensional src (gathers whole slices), enabling e.g. reordering the rows of a matrix by an order computed from a separate key column. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
…t::algorithm::apply_permutation Applying an ordering needs no dedicated function: gather is a std::transform over the index range (or a lazy views::transform), and in-place reordering is boost::algorithm::apply_permutation. Document both idioms in the header instead. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
…olicy overloads Stop hard-coding std::sort. Dispatch the sort through ADL with a std::sort fallback (priority_tag), so thrust::sort is used automatically for thrust iterators without ambiguity (a plain 'using std::sort' would tie with the same-signature thrust::sort). Add overloads taking an execution policy as the first argument (std::execution::par, or a thrust policy), disambiguated via a has_extension trait. Seeding stays a qualified std::copy to keep the ADL surface to just the sort. Verified locally against real thrust (CPP backend), std policies, and the std/pointer fallback. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
…xecution std::execution::seq broke nvcc/nvhpc (header guarded out yet __cpp_lib_execution still defined) and IWYU (demanded internal <pstl/...> headers). Replace with a tiny user-defined policy whose ADL-found sort exercises the policy overload and the ADL-preferred dispatch path directly, with no <execution>/TBB dependency. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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ordering() writes the index permutation that sorts a 1D range without
moving the data; output goes into a caller-provided random-access range
(no internal allocation). Adds test/ordering.cpp.
Co-Authored-By: Claude Opus 4.8 noreply@anthropic.com