You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
108 lines
3.3 KiB
108 lines
3.3 KiB
// David Eberly, Geometric Tools, Redmond WA 98052
|
|
// Copyright (c) 1998-2021
|
|
// Distributed under the Boost Software License, Version 1.0.
|
|
// https://www.boost.org/LICENSE_1_0.txt
|
|
// https://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
|
|
// Version: 4.0.2019.08.13
|
|
|
|
#pragma once
|
|
|
|
#include <Mathematics/IntpAkima1.h>
|
|
|
|
namespace gte
|
|
{
|
|
template <typename Real>
|
|
class IntpAkimaUniform1 : public IntpAkima1<Real>
|
|
{
|
|
public:
|
|
// Construction and destruction. The interpolator is for uniformly
|
|
// spaced x-values.
|
|
IntpAkimaUniform1(int quantity, Real xMin, Real xSpacing, Real const* F)
|
|
:
|
|
IntpAkima1<Real>(quantity, F),
|
|
mXMin(xMin),
|
|
mXSpacing(xSpacing)
|
|
{
|
|
LogAssert(mXSpacing > (Real)0, "Spacing must be positive.");
|
|
|
|
mXMax = mXMin + mXSpacing * static_cast<Real>(quantity - 1);
|
|
|
|
// Compute slopes.
|
|
Real invDX = (Real)1 / mXSpacing;
|
|
std::vector<Real> slope(quantity + 3);
|
|
int i, ip1, ip2;
|
|
for (i = 0, ip1 = 1, ip2 = 2; i < quantity - 1; ++i, ++ip1, ++ip2)
|
|
{
|
|
slope[ip2] = (this->mF[ip1] - this->mF[i]) * invDX;
|
|
}
|
|
|
|
slope[1] = (Real)2 * slope[2] - slope[3];
|
|
slope[0] = (Real)2 * slope[1] - slope[2];
|
|
slope[quantity + 1] = (Real)2 * slope[quantity] - slope[quantity - 1];
|
|
slope[quantity + 2] = (Real)2 * slope[quantity + 1] - slope[quantity];
|
|
|
|
// Construct derivatives.
|
|
std::vector<Real> FDer(quantity);
|
|
for (i = 0; i < quantity; ++i)
|
|
{
|
|
FDer[i] = this->ComputeDerivative(&slope[i]);
|
|
}
|
|
|
|
// Construct polynomials.
|
|
Real invDX2 = (Real)1 / (mXSpacing * mXSpacing);
|
|
Real invDX3 = invDX2 / mXSpacing;
|
|
for (i = 0, ip1 = 1; i < quantity - 1; ++i, ++ip1)
|
|
{
|
|
auto& poly = this->mPoly[i];
|
|
|
|
Real F0 = F[i];
|
|
Real F1 = F[ip1];
|
|
Real df = F1 - F0;
|
|
Real FDer0 = FDer[i];
|
|
Real FDer1 = FDer[ip1];
|
|
|
|
poly[0] = F0;
|
|
poly[1] = FDer0;
|
|
poly[2] = ((Real)3 * df - mXSpacing * (FDer1 + (Real)2 * FDer0)) * invDX2;
|
|
poly[3] = (mXSpacing * (FDer0 + FDer1) - (Real)2 * df) * invDX3;
|
|
}
|
|
}
|
|
|
|
virtual ~IntpAkimaUniform1() = default;
|
|
|
|
// Member access.
|
|
inline virtual Real GetXMin() const override
|
|
{
|
|
return mXMin;
|
|
}
|
|
|
|
inline virtual Real GetXMax() const override
|
|
{
|
|
return mXMax;
|
|
}
|
|
|
|
inline Real GetXSpacing() const
|
|
{
|
|
return mXSpacing;
|
|
}
|
|
|
|
protected:
|
|
virtual void Lookup(Real x, int& index, Real& dx) const override
|
|
{
|
|
// The caller has ensured that mXMin <= x <= mXMax.
|
|
for (index = 0; index + 1 < this->mQuantity; ++index)
|
|
{
|
|
if (x < mXMin + mXSpacing * (index + 1))
|
|
{
|
|
dx = x - (mXMin + mXSpacing * index);
|
|
return;
|
|
}
|
|
}
|
|
|
|
--index;
|
|
dx = x - (mXMin + mXSpacing * index);
|
|
}
|
|
|
|
Real mXMin, mXMax, mXSpacing;
|
|
};
|
|
}
|
|
|