1 /*****************************************************************************
3 Header: FGAirPressureItem.h
4 Author: Christian Mayer
7 ---------- Copyright (C) 1999 Christian Mayer (vader@t-online.de) ----------
9 This program is free software; you can redistribute it and/or modify it under
10 the terms of the GNU General Public License as published by the Free Software
11 Foundation; either version 2 of the License, or (at your option) any later
14 This program is distributed in the hope that it will be useful, but WITHOUT
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
16 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
19 You should have received a copy of the GNU General Public License along with
20 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
21 Place - Suite 330, Boston, MA 02111-1307, USA.
23 Further information about the GNU General Public License can also be found on
24 the world wide web at http://www.gnu.org.
26 FUNCTIONAL DESCRIPTION
27 ------------------------------------------------------------------------------
28 Air pressure item that is stored in the micro weather class
31 ------------------------------------------------------------------------------
32 28.05.1999 Christian Mayer Created
33 08.06.1999 Christian Mayer Added international air preasure formula
34 16.06.1999 Durk Talsma Portability for Linux
35 20.06.1999 Christian Mayer added lots of consts
36 *****************************************************************************/
38 /****************************************************************************/
40 /****************************************************************************/
41 #ifndef FGAirPressureItem_H
42 #define FGAirPressureItem_H
44 /****************************************************************************/
46 /****************************************************************************/
47 #include "FGWeatherDefs.h"
50 /****************************************************************************/
52 /****************************************************************************/
53 class FGAirPressureItem;
54 FGAirPressureItem operator-(const FGAirPressureItem& arg);
56 /****************************************************************************/
57 /* CLASS DECLARATION */
58 /* NOTE: The value stored in 'value' is the air preasure that we'd have at */
59 /* an altitude of 0.0 The correct airpreasure at the stored altitude */
60 /* gets calulated when getValue() is called. */
61 /****************************************************************************/
62 class FGAirPressureItem
65 WeatherPrecition value;
69 FGAirPressureItem(const WeatherPrecition& v) {value = v;}
70 FGAirPressureItem() {value = FG_WEATHER_DEFAULT_AIRPRESSURE;}
72 //WeatherPrecition getValue(WeatherPrecition alt) { return value * pow(1.0 - 0.0065*alt/288.0, 5.255); };
74 WeatherPrecition getValue(const WeatherPrecition& alt) const
76 return (WeatherPrecition)((value / 101325.0) *
78 1.01325e5 + alt * (-1.19459535223623e1 + alt * (5.50461110007561e-4 + alt * (-1.13574703113648e-8 + alt * 8.61601726143988e-14)))
82 FGAirPressureItem& operator*=(const WeatherPrecition& arg);
83 FGAirPressureItem& operator+=(const FGAirPressureItem& arg);
84 FGAirPressureItem& operator-=(const FGAirPressureItem& arg);
86 friend FGAirPressureItem operator-(const FGAirPressureItem& arg);
89 inline FGAirPressureItem& FGAirPressureItem::operator*= (const WeatherPrecition& arg)
95 inline FGAirPressureItem& FGAirPressureItem::operator+= (const FGAirPressureItem& arg)
101 inline FGAirPressureItem& FGAirPressureItem::operator-= (const FGAirPressureItem& arg)
107 inline FGAirPressureItem operator-(const FGAirPressureItem& arg)
109 return FGAirPressureItem(-arg.value);
112 /****************************************************************************/
113 #endif /*FGAirPressureItem_H*/