kstars/kstars/ksutils.cpp

   1 /***************************************************************************
   2                           ksutils.cpp  -  K Desktop Planetarium
   3                              -------------------
   4     begin                : Mon Jan  7 10:48:09 EST 2002
   5     copyright            : (C) 2002 by Mark Hollomon
   6     email                : mhh@mindspring.com
   7  ***************************************************************************/
   8
   9 /***************************************************************************
  10  *                                                                         *
  11  *   This program is free software; you can redistribute it and/or modify  *
  12  *   it under the terms of the GNU General Public License as published by  *
  13  *   the Free Software Foundation; either version 2 of the License, or     *
  14  *   (at your option) any later version.                                   *
  15  *                                                                         *
  16  ***************************************************************************/
  17
  18 #include <kstandarddirs.h>
  19 #include <qfile.h>
  20 #include "ksutils.h"
  21
  22 bool KSUtils::openDataFile( QFile &file, const QString &s ) {
  23         bool result;
  24         QString FileName = locate( "appdata", s );
  25
  26         if ( !FileName.isNull() ) {
  27                 file.setName( FileName );
  28                 if ( !file.open( IO_ReadOnly ) ) {
  29                         result = false;
  30                 } else {
  31                         result = true;
  32                 }
  33         } else {
  34                 result = false;
  35         }
  36
  37         return result;
  38 }
  39
  40 long double KSUtils::lagrangeInterpolation( const long double x[], const long double v[], int n, long double xval) {
  41         long double value = 0;
  42         for (int i=1; i<n; ++i) {
  43                 long double c = 1.0;
  44                 for (int j = 1; j<n;++j)
  45                         if (i != j)
  46                                 c *= (xval - x[j]) / (x[i] - x[j]);
  47                 value += c *v[i];
  48         }
  49
  50         return value;
  51 }