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etaMax.h
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1 // @(#)root/mathcore:$Id$
2 // Authors: W. Brown, M. Fischler, L. Moneta 2005
3 
4  /**********************************************************************
5  * *
6  * Copyright (c) 2005 , FNAL MathLib Team *
7  * *
8  * *
9  **********************************************************************/
10 
11 
12 // Header source file for function etaMax
13 //
14 // Created by: Mark Fischler at Thu Jun 2 2005
15 
16 
17 #ifndef ROOT_Math_GenVector_etaMax
18 #define ROOT_Math_GenVector_etaMax 1
19 
20 
21 #include <limits>
22 #include <cmath>
23 
24 
25 namespace ROOT {
26 
27  namespace Math {
28 
29  /**
30  The following function could be called to provide the maximum possible
31  value of pseudorapidity for a non-zero rho. This is log ( max/min )
32  where max and min are the extrema of positive values for type
33  long double.
34  */
35  inline
36  long double etaMax_impl() {
37  return std::log ( std::numeric_limits<long double>::max()/256.0l ) -
38  std::log ( std::numeric_limits<long double>::denorm_min()*256.0l )
39  + 16.0 * std::log(2.0);
40  // Actual usage of etaMax() simply returns the number 22756, which is
41  // the answer this would supply, rounded to a higher integer.
42  }
43 
44  /**
45  Function providing the maximum possible value of pseudorapidity for
46  a non-zero rho, in the Scalar type with the largest dynamic range.
47  */
48  template <class T>
49  inline
50  T etaMax() {
51  return static_cast<T>(22756.0);
52  }
53 
54  } // namespace Math
55 
56 } // namespace ROOT
57 
58 
59 #endif /* ROOT_Math_GenVector_etaMax */
Namespace for new ROOT classes and functions.
Definition: StringConv.hxx:21
double T(double x)
Definition: ChebyshevPol.h:34
T etaMax()
Function providing the maximum possible value of pseudorapidity for a non-zero rho, in the Scalar type with the largest dynamic range.
Definition: etaMax.h:50
long double etaMax_impl()
The following function could be called to provide the maximum possible value of pseudorapidity for a ...
Definition: etaMax.h:36
Namespace for new Math classes and functions.
auto * l
Definition: textangle.C:4
double log(double)