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cultmath: span tests: a zero-length span through the sloped branch is +0 by bit pattern

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Stryker survivor on the previous head: direction t1 <= t0 changes a zero-length
sloped span from +0 to -0, which no test observed. Builds; test-only.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
This commit is contained in:
Meta Vens 2026-10-16 01:24:20 +02:00
commit e4c1ffa4f1
1 changed files with 7 additions and 1 deletions
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8
packages/cultmath/tests/CultMath.Tests/SpanPrimitiveTests.cs
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@ -322,7 +322,7 @@ public sealed class SpanPrimitiveTests
/// <summary>
/// An infinite bound never reached by the line contributes nothing, not infinity times zero: relu
/// (hi = +inf) and its mirror (lo = -inf) give the finite integral, whether the line crosses the finite
/// bound inside the span or not. The flat branch (b = 0) obeys the same zero-length rule.
/// bound inside the span or not. Both branches give +0 for a zero-length span.
/// </summary>
[Fact]
public void IntegralClampLinearIsFiniteForInfiniteBounds()
@ -352,6 +352,12 @@ public sealed class SpanPrimitiveTests
Assert.Equal(0, BitConverter.SingleToInt32Bits(integral_clamp_linear(1.5f, -0.0f, -inf, -inf, 0.0f, 0.0f)));
Assert.Equal(inf, integral_clamp_linear(1.5f, 0.0f, inf, inf, 0.0f, 2.0f));
Assert.Equal(inf, integral_clamp_linear(1.5f, 0.0f, -inf, -inf, 2.0f, 0.0f));
// The sloped branch gives +0 for a zero-length span too, not -0: the direction sign never meets a
// zero total, whichever way the line leans and whatever the bounds.
Assert.Equal(0, BitConverter.SingleToInt32Bits(integral_clamp_linear(1.0f, 2.0f, -inf, inf, 1.0f, 1.0f)));
Assert.Equal(0, BitConverter.SingleToInt32Bits(integral_clamp_linear(-3.0f, -2.0f, 0.0f, 5.0f, 1.0f, 1.0f)));
Assert.Equal(0, BitConverter.SingleToInt32Bits(integral_clamp_linear(0.5f, 1.0f, 0.0f, inf, 0.0f, 0.0f)));
}
/// <summary>