CGH0S7 699e443c7a Optimize polint/polin2/polin3 interpolation for cache locality ...

Changes:
- polint: Rewrite Neville algorithm from array-slice operations to
  scalar loop. Mathematically identical, avoids temporary array
  allocations for den(1:n-m) slices. (Credit: yx-fmisc branch)

- polin2: Swap interpolation order so inner loop accesses ya(:,j)
  (contiguous in Fortran column-major) instead of ya(i,:) (strided).
  Tensor product interpolation is commutative; all call sites pass
  identical coordinate arrays for all dimensions.

- polin3: Swap interpolation order to process contiguous first
  dimension first: ya(:,j,k) -> yatmp(:,k) -> ymtmp(:).
  Same commutativity argument as polin2.

Compile-time safety switch:
  -DPOLINT_LEGACY_ORDER  restores original dimension ordering
  Default (no flag):     uses optimized contiguous-memory ordering

Usage:
  # Production (optimized order):
  make clean && make -j ABE

  # Fallback if results differ (original order):
  Add -DPOLINT_LEGACY_ORDER to f90appflags in makefile.inc

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

2026-02-06 19:00:35 +08:00

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