105 lines
2.6 KiB
C++
105 lines
2.6 KiB
C++
/**
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* \file interpolater.hxx
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* Routines to handle linear interpolation from a table of x,y The
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* table must be sorted by "x" in ascending order
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*/
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// Written by Curtis Olson, started April 1998.
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//
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// Copyright (C) 1998 Curtis L. Olson - http://www.flightgear.org/~curt
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Library General Public
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// License as published by the Free Software Foundation; either
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// version 2 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Library General Public License for more details.
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//
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// You should have received a copy of the GNU Library General Public
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// License along with this library; if not, write to the
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// Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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// Boston, MA 02111-1307, USA.
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//
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// $Id$
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#ifndef _INTERPOLATER_H
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#define _INTERPOLATER_H
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#ifndef __cplusplus
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# error This library requires C++
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#endif
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#include <simgear/compiler.h>
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#include <vector>
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SG_USING_STD(vector);
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#include STL_STRING
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SG_USING_STD(string);
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/**
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* A class that provids a simple linear 2d interpolation lookup table.
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* The actual table is expected to be loaded from a file. The
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* independant variable must be strictly ascending. The dependent
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* variable can be anything.
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*/
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class SGInterpTable {
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struct Entry
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{
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Entry ()
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: ind(0.0L), dep(0.0L) {}
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Entry (double independent, double dependent)
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: ind(independent), dep(dependent) {}
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double ind;
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double dep;
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};
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int size;
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vector<Entry> table;
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public:
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/**
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* Constructor. Creates a new, empty table.
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*/
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SGInterpTable();
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/**
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* Constructor. Loads the interpolation table from the specified file.
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* @param file name of interpolation file
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*/
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SGInterpTable( const string& file );
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/**
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* Add an entry to the table, extending the table's length.
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*
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* @param ind The independent variable.
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* @param dep The dependent variable.
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*/
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void addEntry (double ind, double dep);
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/**
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* Given an x value, linearly interpolate the y value from the table.
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* @param x independent variable
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* @return interpolated dependent variable
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*/
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double interpolate(double x) const;
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/** Destructor */
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~SGInterpTable();
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};
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#endif // _INTERPOLATER_H
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