29657734573
85%
master: 84%

Ran 18 Jul 2026 08:06PM UTC

Jobs 1

Files 695

Run time 1min

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Committed 18 Jul 2026 07:24PM UTC coverage: 84.697% (-0.003%) from 84.7%

Build # 29657734573

Build Type

push

github

Committed by

web-flow

Commit Message

feat(efloat): catastrophic cancellation demonstration (#1096) (#1145)

Adds applications/precision/adaptive/catastrophic_cancellation.cpp: a templated
kernel that runs the same code on double and efloat to show how adaptive
precision defeats catastrophic cancellation.

f(x) = (1 - cos x)/x^2 is numerically unstable for small x (cos x ~ 1, so the
subtraction loses its significant digits); g(x) = 2 sin^2(x/2)/x^2 is the stable,
algebraically identical form. Both tend to 1/2 as x -> 0. At x = 1e-10 double
f(x) collapses to 0 (100% error) while efloat<8> (256-bit) f(x) returns 0.5 from
the SAME unstable formula, and efloat f and g agree to ~192 bits. A breakdown
table across x = 1e-2 .. 1e-14 shows double f's relative error climbing from
~3e-13 to 1.0 while efloat f stays accurate.

Note: efloat's operator<< is still a TBD stub, so values print via double() casts
and agreement is shown via the scale metric; that is sufficient to make the
point and avoids depending on the streaming path.

Wires a new applications/precision/adaptive/ directory (CMakeLists mirrors the
sibling precision examples; add_subdirectory added to the root applications
block). Builds and runs on gcc 13.3.0 and clang 18.1.3.

Resolves #1096

Coverage Stats

49474 of 58413 relevant lines covered (84.7%)

6894740.64 hits per line

Coverage Regressions

Lines	Coverage	∆	File
10	31.43	-3.57%	include/sw/universal/verification/test_suite_randoms.hpp
2	89.78	0.0%	include/sw/universal/number/posito/posito_impl.hpp

Jobs

ID	Job ID	Ran	Files	Coverage
1	29657734573.1	18 Jul 2026 08:06PM UTC	695	84.7	GitHub Action Run

stillwater-sc / universal / 29657734573
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master: 84%

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