span_slack and af_snoise each spelled 2^-14 (value) and 2^-12 (gradient) inline, in C# and
HLSL. Both now read the constants beside SNOISE_HESSIAN (math.Affine.cs, CultMath.Affine.hlsl,
Unity copies), so a device-judged widening moves every reader. Bits unchanged. The test
oracles in AffineTests and GlslMirrorTests read the constants; a new test pins af_snoise's
allowance to span_slack's terms. span_slack's comment no longer claims it is the only
allowance. Does not build green yet: CultMath.glsl is not regenerated in this commit.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
ThirdTensor is now snoise_hessian's per-corner derivation differentiated once more, in double, on the
kernel's lattice, tie order and hash; central differences of the float Hessian are gone from the
measurement and survive only as the oracle in ThirdTensorMatchesDifferencesOfTheHessian (Richardson
extrapolated differences of the double Hessian). MeasureThird on the closed form: refined 487.0917,
x 1.10 = 535.8009 (the differenced tensor read 488.1047, its roundoff). SNOISE_THIRD, ThirdWitness,
CULTMATH_SNOISE_THIRD (both HLSL copies), the generated GLSL constant and the design.md provenance
paragraph follow.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
MeasureThird on the tied kernel: refined 488.1047, x 1.10 = 536.9152, witness (-168.3755, -3.8205261,
-109.16948). MeasureHessian with the analytic Hessian: refined 50.58377, x 1.10 = 55.642143, witness
(-13.7920685, -9.672134, 61.563934); the central-difference value 56.050385 carried the quotient's
roundoff. README bullet for the span primitives. CultMath.glsl and the fixture are not yet regenerated.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
math.Span.cs adds the analytic Hessian of snoise(float3) on snoise_grad's tied kernel and the closed-form
integral of a clamped linear ramp; HLSL twins and the Unity copies follow, HessianNorm now reads the
library Hessian, the GLSL lowering gains float3x3 to mat3, and MeasureThird/ThirdConstantPinsSampled and
SpanPrimitiveTests land. SNOISE_THIRD is a placeholder (1) until MeasureThird runs; CultMath.glsl and the
fixture are not yet regenerated. Does not pass its tests.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
dxc marks compares fast, so `lo == lo ? lo : -inf` was deleted under default flags and an
overflowed form ranged to NaN on HLSL targets. The guard now tests (asuint(lo) & 0x7fffffff)
> 0x7f800000, in HLSL, the Unity copy, math.Affine.cs and the regenerated CultMath.glsl.
dxc 1.9.0.5402 -T ps_6_0 default flags: before, no fcmp/select/and in the af_range body;
after, and/icmp ugt/select to +-inf for both endpoints (also under -Gis).
AffineRangeMirrorMatchesCSharpBitForBitAtTheFloatExtremes pins the mirror at zero to the
float maximum, infinities and NaN components.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
