From ecd06267d011d9b017e3cada08bad867b6c64d20 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christoph=20Gr=C3=BCninger?=
<christoph.grueninger@iws.uni-stuttgart.de>
Date: Tue, 29 Nov 2016 15:50:42 +0100
Subject: [PATCH] Use cbrt instead of pow(. ,1/3)
---
dumux/common/dimensionlessnumbers.hh | 4 +++-
dumux/common/math.hh | 19 ++++++++++---------
2 files changed, 13 insertions(+), 10 deletions(-)
diff --git a/dumux/common/dimensionlessnumbers.hh b/dumux/common/dimensionlessnumbers.hh
index 6a50bf2f5b..2934f884d6 100644
--- a/dumux/common/dimensionlessnumbers.hh
+++ b/dumux/common/dimensionlessnumbers.hh
@@ -264,7 +264,9 @@ static Scalar sherwoodNumber(const Scalar reynoldsNumber,
/* example: flow through porous medium *single phase*
* Wakao and Kaguei, Heat and mass Transfer in Packed Beds, Gordon and Breach Science Publishers, page 156
*/
- return 2. + 1.1 * pow(schmidtNumber,(1./3.)) * pow(reynoldsNumber, 0.6);
+ using std::cbrt;
+ using std::pow;
+ return 2. + 1.1 * cbrt(schmidtNumber) * pow(reynoldsNumber, 0.6);
}
else {
diff --git a/dumux/common/math.hh b/dumux/common/math.hh
index 20d4e611b0..8c54aeaab0 100644
--- a/dumux/common/math.hh
+++ b/dumux/common/math.hh
@@ -239,9 +239,8 @@ int invertCubicPolynomial(SolContainer *sol,
// t^3 + q = 0,
//
// i. e. single real root at t=curt(q)
- Scalar t;
- if (-q > 0) t = std::pow(-q, 1./3);
- else t = - std::pow(q, 1./3);
+ using std::cbrt;
+ Scalar t = cbrt(q);
sol[0] = t - b/3;
return 1;
@@ -256,9 +255,10 @@ int invertCubicPolynomial(SolContainer *sol,
}
// two additional real roots at t = sqrt(-p) and t = -sqrt(-p)
- sol[0] = -std::sqrt(-p) - b/3;
+ using std::sqrt;
+ sol[0] = -sqrt(-p) - b/3;
sol[1] = 0.0 - b/3;
- sol[2] = std::sqrt(-p) - b/3;
+ sol[2] = sqrt(-p) - b/3;
return 3;
}
@@ -296,9 +296,9 @@ int invertCubicPolynomial(SolContainer *sol,
Scalar wDisc = q*q/4 + p*p*p/27;
if (wDisc >= 0) { // the positive discriminant case:
// calculate the cube root of - q/2 + sqrt(q^2/4 + p^3/27)
- Scalar u = - q/2 + std::sqrt(wDisc);
- if (u < 0) u = - std::pow(-u, 1.0/3);
- else u = std::pow(u, 1.0/3);
+ using std::cbrt;
+ using std::sqrt;
+ Scalar u = cbrt(-q/2 + sqrt(wDisc));
// at this point, u != 0 since p^3 = 0 is necessary in order
// for u = 0 to hold, so
@@ -314,7 +314,8 @@ int invertCubicPolynomial(SolContainer *sol,
using std::sqrt;
Scalar uCubedIm = sqrt(-wDisc);
// calculate the cube root of - q/2 + sqrt(q^2/4 + p^3/27)
- Scalar uAbs = std::pow(std::sqrt(uCubedRe*uCubedRe + uCubedIm*uCubedIm), 1.0/3);
+ using std::cbrt;
+ Scalar uAbs = cbrt(sqrt(uCubedRe*uCubedRe + uCubedIm*uCubedIm));
using std::atan2;
Scalar phi = atan2(uCubedIm, uCubedRe)/3;
--
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