mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-25 09:18:54 -05:00
101 lines
3.2 KiB
C++
101 lines
3.2 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2021 Jon Beniston, M7RCE //
|
|
// //
|
|
// This program is free software; you can redistribute it and/or modify //
|
|
// it under the terms of the GNU General Public License as published by //
|
|
// the Free Software Foundation as version 3 of the License, or //
|
|
// (at your option) any later version. //
|
|
// //
|
|
// This program is distributed in the hope that it will be useful, //
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of //
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
|
|
// GNU General Public License V3 for more details. //
|
|
// //
|
|
// You should have received a copy of the GNU General Public License //
|
|
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
|
|
///////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#ifndef INCLUDE_INTERPOLATION_H
|
|
#define INCLUDE_INTERPOLATION_H
|
|
|
|
#include "export.h"
|
|
#include <iterator>
|
|
|
|
class SDRBASE_API Interpolation {
|
|
public:
|
|
|
|
// Linear interpolation/extrapolation
|
|
// Assumes x is sorted in increasing order
|
|
template<class Iter, class T>
|
|
static T linear(Iter xBegin, Iter xEnd, Iter yBegin, T x)
|
|
{
|
|
// Find first point in x that target is bigger than
|
|
int i = 0;
|
|
while (xBegin != xEnd)
|
|
{
|
|
if (x < *xBegin) {
|
|
break;
|
|
}
|
|
++xBegin;
|
|
i++;
|
|
}
|
|
T x0, x1, y0, y1;
|
|
if (i == 0) {
|
|
// Extrapolate left
|
|
x0 = *xBegin;
|
|
++xBegin;
|
|
x1 = *xBegin;
|
|
y0 = *yBegin;
|
|
++yBegin;
|
|
y1 = *yBegin;
|
|
|
|
return extrapolate(x0, y0, x1, y1, x);
|
|
} else if (xBegin > xEnd) {
|
|
// Extrapolate right
|
|
Iter xCur = xBegin;
|
|
std::advance(xCur, i - 2);
|
|
x0 = *xCur;
|
|
++xCur;
|
|
x1 = *xCur;
|
|
|
|
Iter yCur = yBegin;
|
|
std::advance(yCur, i - 2);
|
|
y0 = *yCur;
|
|
++yCur;
|
|
y1 = *yCur;
|
|
|
|
return extrapolate(x0, y0, x1, y1, x);
|
|
} else {
|
|
// Interpolate
|
|
x1 = *xBegin;
|
|
--xBegin;
|
|
x0 = *xBegin;
|
|
|
|
Iter yCur = yBegin;
|
|
std::advance(yCur, i - 1);
|
|
y0 = *yCur;
|
|
++yCur;
|
|
y1 = *yCur;
|
|
|
|
return interpolate(x0, y0, x1, y1, x);
|
|
}
|
|
}
|
|
|
|
// Linear extrapolation
|
|
template<class T>
|
|
static T extrapolate(T x0, T y0, T x1, T y1, T x)
|
|
{
|
|
return y0 + ((x-x0)/(x1-x0)) * (y1-y0);
|
|
}
|
|
|
|
// Linear interpolation
|
|
template<class T>
|
|
static T interpolate(T x0, T y0, T x1, T y1, T x)
|
|
{
|
|
return (y0*(x1-x) + y1*(x-x0)) / (x1-x0);
|
|
}
|
|
|
|
};
|
|
|
|
#endif // INCLUDE_INTERPOLATION_H
|