From fec96cdfa617e0464faa9d5f3a1d7e3d52719ef8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dennis=20Gl=C3=A4ser?= <dennis.glaeser@iws.uni-stuttgart.de>
Date: Thu, 28 Sep 2023 16:17:29 +0000
Subject: [PATCH] [timeloop] add comment on setDt check
---
dumux/common/timeloop.hh | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/dumux/common/timeloop.hh b/dumux/common/timeloop.hh
index 7b4098e7b9..2038555384 100644
--- a/dumux/common/timeloop.hh
+++ b/dumux/common/timeloop.hh
@@ -245,6 +245,12 @@ public:
{
using std::min;
timeStepSize_ = min(dt, maxTimeStepSize());
+ // Warn if dt is so small w.r.t. current time that it renders float addition meaningless
+ // For instance, consider (may depend on architecture):
+ // double cien = 100;
+ // double mil = 1000;
+ // if (cien + 1e-14 == cien) std::cout << "Will not be printed" << std::endl;
+ // if (mil + 1e-14 == mil) std::cout << "Will be printed" << std::endl;
if (!finished() && (time_ + timeStepSize_ == time_))
std::cerr << Fmt::format("You have set a very small timestep size (dt = {:.5g}).", timeStepSize_)
<< " This might lead to numerical problems!\n";
--
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