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
mnbins(double a1,double a2,int naa,double & bl,double & bh,int & nb,double & bwid)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
111