feat: add the inverse Gaussian (Wald) distribution - #423

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agene0001 wants to merge 12 commits into

statrs-dev:mainfrom

agene0001:feat/371-inverse-gaussian

Commits on Jul 26, 2026

fix: stop prec::ulps_eq! degenerating into a 1e-9 absolute comparison
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a6a4822
fix: restore full precision to erf's interval constants
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fdc7c50
fix: evaluate the Lanczos sum in a well-conditioned form
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c4e9de9
fix: scale beta_reg's continued-fraction bound with its parameters
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32b6618
fix: use Loader's saddle-point form for the gamma/beta prefixes and pmfs
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cc54f46
merge: erf constant fix, which the tail compensation depends on
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a324623
fix: compensate the argument rounding in Normal's cdf/sf tails
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e28b16a
feat: add ln_cdf and ln_sf with tail-accurate implementations
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9d29d52
feat: add the inverse Gaussian (Wald) distribution

agene0001
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claude
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30cd084

Commits on Jul 28, 2026

fix: use hardware FMA where available, and stop discarding the residual

agene0001
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claude
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89c1d12

Commits on Jul 29, 2026

fix: mode cancellation, a NaN sample, and FMA detection

agene0001
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claude
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d10da15
fix: compensate the square in erfcx's negative branch

agene0001
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claude
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a588658