sc/inc/kahan.hxx | 40 ++++++++++++++++++++++++++++++++++++++-
sc/source/core/tool/interpr3.cxx | 26 ++++++++++++++-----------
2 files changed, 54 insertions(+), 12 deletions(-)
New commits:
commit 94977bb43d8dc91023bee7afa037f6319c36ccc3
Author: dante <dante19031...@gmail.com>
AuthorDate: Sat May 1 11:04:21 2021 +0200
Commit: Mike Kaganski <mike.kagan...@collabora.com>
CommitDate: Tue May 4 20:34:11 2021 +0200
tdf#137679 Use kahan summation for ScInterpreter::lcl_IterateInverse
Change-Id: I02e108ac70ddd4ea8d8d97eb4f5fbc8996dd4bd1
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/114966
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kagan...@collabora.com>
diff --git a/sc/inc/kahan.hxx b/sc/inc/kahan.hxx
index ffeeab0867df..23a29f6ee13f 100644
--- a/sc/inc/kahan.hxx
+++ b/sc/inc/kahan.hxx
@@ -53,6 +53,16 @@ public:
add(fSum.m_fError);
}
+ /**
+ * Substracts a value to the sum using Kahan summation.
+ * @param fSum
+ */
+ inline void subtract(const KahanSum& fSum)
+ {
+ add(-fSum.m_fSum);
+ add(-fSum.m_fError);
+ }
+
public:
constexpr KahanSum operator-() const
{
@@ -75,7 +85,7 @@ public:
inline void operator+=(double fSum) { add(fSum); }
- inline void operator-=(const KahanSum& fSum) { add(-fSum); }
+ inline void operator-=(const KahanSum& fSum) { subtract(fSum); }
inline void operator-=(double fSum) { add(-fSum); }
@@ -86,6 +96,13 @@ public:
return fNSum;
}
+ inline KahanSum operator+(const KahanSum& fSum) const
+ {
+ KahanSum fNSum(*this);
+ fNSum += fSum;
+ return fNSum;
+ }
+
inline KahanSum operator-(double fSum) const
{
KahanSum fNSum(*this);
@@ -93,6 +110,13 @@ public:
return fNSum;
}
+ inline KahanSum operator-(const KahanSum& fSum) const
+ {
+ KahanSum fNSum(*this);
+ fNSum -= fSum;
+ return fNSum;
+ }
+
/**
* In some parts of the code of interpr_.cxx this may be used for
* product instead of sum. This operator shall be used for that task.
@@ -109,6 +133,20 @@ public:
m_fError /= fDivides;
}
+ constexpr KahanSum operator*(double fTimes) const
+ {
+ KahanSum fSum(*this);
+ fSum *= fTimes;
+ return fSum;
+ }
+
+ constexpr KahanSum operator/(double fTimes) const
+ {
+ KahanSum fSum(*this);
+ fSum /= fTimes;
+ return fSum;
+ }
+
constexpr bool operator<(const KahanSum& fSum) const { return get() <
fSum.get(); }
constexpr bool operator<(double fSum) const { return get() < fSum; }
diff --git a/sc/source/core/tool/interpr3.cxx b/sc/source/core/tool/interpr3.cxx
index 17fe63381362..c339a68dd80f 100644
--- a/sc/source/core/tool/interpr3.cxx
+++ b/sc/source/core/tool/interpr3.cxx
@@ -84,32 +84,36 @@ static double lcl_IterateInverse( const ScDistFunc&
rFunction, double fAx, doubl
// find enclosing interval
+ KahanSum fkAx = fAx;
+ KahanSum fkBx = fBx;
double fAy = rFunction.GetValue(fAx);
double fBy = rFunction.GetValue(fBx);
- double fTemp;
+ KahanSum fTemp;
unsigned short nCount;
for (nCount = 0; nCount < 1000 && !lcl_HasChangeOfSign(fAy,fBy); nCount++)
{
if (std::abs(fAy) <= std::abs(fBy))
{
- fTemp = fAx;
- fAx += 2.0 * (fAx - fBx);
- if (fAx < 0.0)
- fAx = 0.0;
- fBx = fTemp;
+ fTemp = fkAx;
+ fkAx += (fkAx - fkBx) * 2.0;
+ if (fkAx < 0.0)
+ fkAx = 0.0;
+ fkBx = fTemp;
fBy = fAy;
- fAy = rFunction.GetValue(fAx);
+ fAy = rFunction.GetValue(fkAx.get());
}
else
{
- fTemp = fBx;
- fBx += 2.0 * (fBx - fAx);
- fAx = fTemp;
+ fTemp = fkBx;
+ fkBx += (fkBx - fkAx) * 2.0;
+ fkAx = fTemp;
fAy = fBy;
- fBy = rFunction.GetValue(fBx);
+ fBy = rFunction.GetValue(fkBx.get());
}
}
+ fAx = fkAx.get();
+ fBx = fkBx.get();
if (fAy == 0.0)
return fAx;
if (fBy == 0.0)
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