From a79af2f3c9a13375119ebee26501b8b3b9ba866a Mon Sep 17 00:00:00 2001
From: Yonghui <huangyh56@gmail.com>
Date: Mon, 10 Oct 2016 18:17:58 +0200
Subject: [PATCH] update the getDerivative function and update g-test
---
.../PiecewiseLinearInterpolation.cpp | 37 +++++++++++++------
.../PiecewiseLinearInterpolation.h | 2 +
.../TestPiecewiseLinearInterpolation.cpp | 7 +++-
3 files changed, 34 insertions(+), 12 deletions(-)
diff --git a/MathLib/InterpolationAlgorithms/PiecewiseLinearInterpolation.cpp b/MathLib/InterpolationAlgorithms/PiecewiseLinearInterpolation.cpp
index a314121459a..cf984006af5 100644
--- a/MathLib/InterpolationAlgorithms/PiecewiseLinearInterpolation.cpp
+++ b/MathLib/InterpolationAlgorithms/PiecewiseLinearInterpolation.cpp
@@ -72,29 +72,44 @@ double PiecewiseLinearInterpolation::getDerivative(
auto const& it(std::lower_bound(_supp_pnts.begin(), _supp_pnts.end(),
pnt_to_interpolate));
- std::size_t const interval_idx = std::distance(_supp_pnts.begin(), it) - 1;
+ std::size_t interval_idx = std::distance(_supp_pnts.begin(), it);
+
+ if (pnt_to_interpolate == _supp_pnts.front())
+ {
+ interval_idx = 1;
+ }
- // interval_idx = interval_max - 1 - interval_idx;
- if (interval_idx > 1 && interval_idx < _supp_pnts.size() - 2)
+ if (interval_idx > 2 && interval_idx < _supp_pnts.size() - 1)
{
double const tangent_right =
- (_values_at_supp_pnts[interval_idx] -
- _values_at_supp_pnts[interval_idx + 2]) /
- (_supp_pnts[interval_idx] - _supp_pnts[interval_idx + 2]);
- double const tangent_left =
(_values_at_supp_pnts[interval_idx - 1] -
_values_at_supp_pnts[interval_idx + 1]) /
(_supp_pnts[interval_idx - 1] - _supp_pnts[interval_idx + 1]);
+ double const tangent_left =
+ (_values_at_supp_pnts[interval_idx - 2] -
+ _values_at_supp_pnts[interval_idx]) /
+ (_supp_pnts[interval_idx - 2] - _supp_pnts[interval_idx]);
double const w =
- (pnt_to_interpolate - _supp_pnts[interval_idx + 1]) /
- (_supp_pnts[interval_idx] - _supp_pnts[interval_idx + 1]);
+ (pnt_to_interpolate - _supp_pnts[interval_idx]) /
+ (_supp_pnts[interval_idx - 1] - _supp_pnts[interval_idx]);
return (1. - w) * tangent_right + w * tangent_left;
}
else
{
return (_values_at_supp_pnts[interval_idx] -
- _values_at_supp_pnts[interval_idx + 1]) /
- (_supp_pnts[interval_idx] - _supp_pnts[interval_idx + 1]);
+ _values_at_supp_pnts[interval_idx - 1]) /
+ (_supp_pnts[interval_idx] - _supp_pnts[interval_idx - 1]);
}
}
+
+double PiecewiseLinearInterpolation::getSupportMax() const
+{
+ assert(!_supp_pnts.empty());
+ return _supp_pnts.back();
+}
+double PiecewiseLinearInterpolation::getSupportMin() const
+{
+ assert(!_supp_pnts.empty());
+ return _supp_pnts.front();
+}
} // end MathLib
diff --git a/MathLib/InterpolationAlgorithms/PiecewiseLinearInterpolation.h b/MathLib/InterpolationAlgorithms/PiecewiseLinearInterpolation.h
index 7a38a80a5af..1a66e4d7c3a 100644
--- a/MathLib/InterpolationAlgorithms/PiecewiseLinearInterpolation.h
+++ b/MathLib/InterpolationAlgorithms/PiecewiseLinearInterpolation.h
@@ -75,6 +75,8 @@ public:
* using linear interpolation.
*/
double getDerivative(double const pnt_to_interpolate) const;
+ double getSupportMax() const;
+ double getSupportMin() const;
private:
std::vector<double> _supp_pnts;
diff --git a/Tests/MathLib/TestPiecewiseLinearInterpolation.cpp b/Tests/MathLib/TestPiecewiseLinearInterpolation.cpp
index e29fc0e0fc7..914d781e83d 100644
--- a/Tests/MathLib/TestPiecewiseLinearInterpolation.cpp
+++ b/Tests/MathLib/TestPiecewiseLinearInterpolation.cpp
@@ -131,7 +131,7 @@ TEST(MathLibInterpolationAlgorithms, PiecewiseLinearInterpolationDerivative)
for (std::size_t k(0); k < size; ++k)
{
supp_pnts.push_back(static_cast<double>(k));
- values.push_back(k * k);
+ values.push_back(static_cast<double>(k * k));
}
MathLib::PiecewiseLinearInterpolation interpolation{std::move(supp_pnts),
@@ -142,6 +142,11 @@ TEST(MathLibInterpolationAlgorithms, PiecewiseLinearInterpolationDerivative)
ASSERT_NEAR(1 + 2 * k, interpolation.getDerivative(k + 0.5),
std::numeric_limits<double>::epsilon());
}
+ // max and min value test
+ ASSERT_NEAR(1, interpolation.getDerivative(0),
+ std::numeric_limits<double>::epsilon());
+ ASSERT_NEAR(1997, interpolation.getDerivative(999),
+ std::numeric_limits<double>::epsilon());
// Extrapolation
ASSERT_NEAR(0, interpolation.getDerivative(-1),
--
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