Replace trueimpes' hard-coded pressure_scale with row equilibration - #7285
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Replace trueimpes' hard-coded pressure_scale with row equilibration#7285hnil wants to merge 1 commit into
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The 50e5 factor on the pressure row of block_transpose was a no-op in exact arithmetic: the rhs of the local solve is a unit vector, so scaling row p by s yields w = B^-T e_p / s, and the subsequent abs_max normalisation divides the factor straight back out. Its only effect was to condition the small dense solve, since the pressure row of a storage derivative is tiny relative to the others. Equilibrate all rows to unit max magnitude instead, with power-of-two factors so the scaling introduces no rounding. Same cancellation argument, no magic constant, and every row is conditioned rather than just the pressure one. Verified behaviour-neutral on SPE1CASE1 (trueimpes 383/322/445 -> 376/317/440; default cprw 443 -> 437 - pivoting noise). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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August 7, 2026 15:35
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The 50e5 factor on the pressure row of the local trueimpes solve is a no-op in exact arithmetic: the rhs is a unit vector, so any row scaling cancels in the abs_max normalisation. Replace it with a power-of-two equilibration of all rows, which conditions the small dense solve without a magic constant. Verified behaviour-neutral on SPE1CASE1 and SPE9_CP (iteration shifts at pivoting-noise level, SPE9 cprw unchanged at 439).
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