From 41f0b78cbf204649bbae71662a115425c58f048d Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Thu, 14 Mar 2019 02:25:26 -0700 Subject: Simplify overlap() formula for case where variances are equal (GH-12323) --- Lib/statistics.py | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Lib/statistics.py b/Lib/statistics.py index 97f1543..8d79eed 100644 --- a/Lib/statistics.py +++ b/Lib/statistics.py @@ -773,7 +773,7 @@ class NormalDist: dv = Y_var - X_var dm = fabs(Y.mu - X.mu) if not dv: - return 2.0 * NormalDist(dm, 2.0 * X.sigma).cdf(0) + return 1.0 - erf(dm / (2.0 * X.sigma * sqrt(2.0))) a = X.mu * Y_var - Y.mu * X_var b = X.sigma * Y.sigma * sqrt(dm**2.0 + dv * log(Y_var / X_var)) x1 = (a + b) / dv -- cgit v0.12