bin_size.h

00001 /*
00002   -------------------------------------------------------------------
00003   
00004   Copyright (C) 2006, 2007, Andrew W. Steiner
00005   
00006   This file is part of O2scl.
00007   
00008   O2scl is free software; you can redistribute it and/or modify
00009   it under the terms of the GNU General Public License as published by
00010   the Free Software Foundation; either version 3 of the License, or
00011   (at your option) any later version.
00012   
00013   O2scl is distributed in the hope that it will be useful,
00014   but WITHOUT ANY WARRANTY; without even the implied warranty of
00015   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00016   GNU General Public License for more details.
00017   
00018   You should have received a copy of the GNU General Public License
00019   along with O2scl. If not, see <http://www.gnu.org/licenses/>.
00020 
00021   -------------------------------------------------------------------
00022 */
00023 #ifndef O2SCL_BIN_SIZE_H
00024 #define O2SCL_BIN_SIZE_H
00025 
00026 #include <iostream>
00027 #include <cmath>
00028 
00029 #ifndef DOXYGENP
00030 namespace o2scl {
00031 #endif
00032 
00033   /** 
00034       \brief Determine bin size (CERNLIB)
00035 
00036       This is adapted from the KERNLIB routine \c binsiz.f written by
00037       F. James. 
00038       
00039       This class computes an appropriate set of histogram bins given the
00040       upper and lower limits of the data and the maximum number of bins.
00041       The bin width is always an integral power of ten times 1, 2, 2.5 
00042       or 5. The bin width may also be specified by the user, in which
00043       case the class only computes the appropriate limits.
00044       
00045       \todo Doesn't seem to be working yet.
00046   */
00047   class bin_size {
00048 
00049   public:
00050 
00051     bin_size() {
00052       cern_mode=true;
00053     }
00054 
00055     /// (default true) 
00056     bool cern_mode;
00057 
00058     /**
00059        \brief Compute bin size
00060 
00061        - \c al - Lower limit of data
00062        - \c ah - Upper limit of data
00063        - \c na - Maximum number of bins desired. 
00064        - \c bl - Lower limit (BL<=AL)
00065        - \c bh - Upper limit (BH>=AH)
00066        - \c nb - Number of bins determined by BINSIZ (NA/2<NB<=NA)
00067        - \c bwid - Bin width (BH-BL)/NB
00068       
00069        If \c na=0 or \c na=-1, this function always makes exactly 
00070        one bin.
00071        
00072        If \c na=1, this function takes \c bwid as input and determines
00073        only \c bl, \c hb, and \c nb. This is especially useful when it is
00074        desired to have the same bin width for several histograms (or
00075        for the two axes of a scatter-plot).
00076        
00077        If \c al > \c ah, this function takes \c al to be the upper
00078        limit and \c ah to be the lower limit, so that in fact \c al
00079        and \c ah may appear in any order. They are not changed by
00080        calc_bin(). If \c al = \c ah, the lower limit is taken to be \c al,
00081        and the upper limit is set to \c al+1.
00082 
00083        If \ref cern_mode is true (which is the default) the starting
00084        guess for the number of bins is \c na-1. Otherwise, the 
00085        starting guess for the number of bins is \c na. 
00086       
00087     */
00088     int calc_bin(double al, double ah, int na, double &bl, double &bh, 
00089                  int &nb, double &bwid);
00090       
00091   };
00092 
00093 #ifndef DOXYGENP
00094 }
00095 #endif
00096 
00097 #endif

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