[Flexiblesusy-commits] [FlexibleSUSY/FlexibleSUSY] 63f536: fix numerical stability of B1 function

[GitHub]

  Branch: refs/heads/development
  Home:   https://github.com/FlexibleSUSY/FlexibleSUSY
  Commit: 63f5361c1a3d7a5992dfc54fd1934779e6b5dd00
      https://github.com/FlexibleSUSY/FlexibleSUSY/commit/63f5361c1a3d7a5992dfc54fd1934779e6b5dd00
  Author: Alexander Voigt <Alexander.Voigt at desy.de>
  Date:   2016-07-05 (Tue, 05 Jul 2016)

  Changed paths:
    M src/numerics.cpp

  Log Message:
  -----------
  fix numerical stability of B1 function

for scenarios with

   m1 = 1e5, m2 = m1 + 0.13, q = m1,
   p = 0 ... 500

In this scenario, m1 is close to m2.  Therfore, the p^2 terms are
divided by the small quantity (m1^2 - m2^2), which leads to an
instability.

The fix is to catch the case when m1 ~ m2.