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mnbins.cxx
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1 // @(#)root/minuit2:$Id$
2 // Authors: M. Winkler, F. James, L. Moneta, A. Zsenei 2003-2005
3 
4 /**********************************************************************
5  * *
6  * Copyright (c) 2005 LCG ROOT Math team, CERN/PH-SFT *
7  * *
8  **********************************************************************/
9 
10 #include <cmath>
11 
12 namespace ROOT {
13 
14 namespace Minuit2 {
15 
16 void mnbins(double a1, double a2, int naa, double &bl, double &bh, int &nb, double &bwid)
17 {
18 
19  //*-*-*-*-*-*-*-*-*-*-*Compute reasonable histogram intervals*-*-*-*-*-*-*-*-*
20  //*-* ======================================
21  //*-* Function TO DETERMINE REASONABLE HISTOGRAM INTERVALS
22  //*-* GIVEN ABSOLUTE UPPER AND LOWER BOUNDS A1 AND A2
23  //*-* AND DESIRED MAXIMUM NUMBER OF BINS NAA
24  //*-* PROGRAM MAKES REASONABLE BINNING FROM BL TO BH OF WIDTH BWID
25  //*-* F. JAMES, AUGUST, 1974 , stolen for Minuit, 1988
26  //*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
27 
28  /* Local variables */
29  double awid, ah, al, sigfig, sigrnd, alb;
30  int kwid, lwid, na = 0, log_;
31 
32  al = a1 < a2 ? a1 : a2;
33  // al = std::min(a1,a2);
34  // ah = std::max(a1,a2);
35  ah = a1 > a2 ? a1 : a2;
36  if (al == ah)
37  ah = al + 1;
38 
39  //*-*- IF NAA .EQ. -1 , PROGRAM USES BWID INPUT FROM CALLING ROUTINE
40  if (naa == -1)
41  goto L150;
42 L10:
43  na = naa - 1;
44  if (na < 1)
45  na = 1;
46 
47  //*-*- GET NOMINAL BIN WIDTH IN EXPON FORM
48 L20:
49  awid = (ah - al) / double(na);
50  log_ = int(log10(awid));
51  if (awid <= 1)
52  --log_;
53  sigfig = awid * pow(10.0, -log_);
54  //*-*- ROUND MANTISSA UP TO 2, 2.5, 5, OR 10
55  if (sigfig > 2)
56  goto L40;
57  sigrnd = 2;
58  goto L100;
59 L40:
60  if (sigfig > 2.5)
61  goto L50;
62  sigrnd = 2.5;
63  goto L100;
64 L50:
65  if (sigfig > 5)
66  goto L60;
67  sigrnd = 5;
68  goto L100;
69 L60:
70  sigrnd = 1;
71  ++log_;
72 L100:
73  bwid = sigrnd * pow(10.0, log_);
74  goto L200;
75  //*-*- GET NEW BOUNDS FROM NEW WIDTH BWID
76 L150:
77  if (bwid <= 0)
78  goto L10;
79 L200:
80  alb = al / bwid;
81  lwid = int(alb);
82  if (alb < 0)
83  --lwid;
84  bl = bwid * double(lwid);
85  alb = ah / bwid + 1;
86  kwid = int(alb);
87  if (alb < 0)
88  --kwid;
89  bh = bwid * double(kwid);
90  nb = kwid - lwid;
91  if (naa > 5)
92  goto L240;
93  if (naa == -1)
94  return;
95  //*-*- REQUEST FOR ONE BIN IS DIFFICULT CASE
96  if (naa > 1 || nb == 1)
97  return;
98  bwid *= 2;
99  nb = 1;
100  return;
101 L240:
102  if (nb << 1 != naa)
103  return;
104  ++na;
105  goto L20;
106 } /* mnbins_ */
107 
108 } // namespace Minuit2
109 
110 } // namespace ROOT
log10
double log10(double)
ROOT::Minuit2::mnbins
void mnbins(double a1, double a2, int naa, double &bl, double &bh, int &nb, double &bwid)
Definition: mnbins.cxx:16
double
double
Definition: Converters.cxx:921
pow
double pow(double, double)
ROOT
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