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 // @(#)root/base:
 // Authors: Rene Brun, Fons Rademakers   29/07/95
 
 /*************************************************************************
  * Copyright (C) 1995-2004, Rene Brun and Fons Rademakers.               *
  * All rights reserved.                                                  *
  *                                                                       *
  * For the licensing terms see $ROOTSYS/LICENSE.                         *
  * For the list of contributors see $ROOTSYS/README/CREDITS.             *
  *************************************************************************/
 
 #ifndef ROOT_TMathBase
 #define ROOT_TMathBase
 
 
 //////////////////////////////////////////////////////////////////////////
 //                                                                      //
 // TMath Base functions                                                 //
 //                                                                      //
 // Define the functions Min, Max, Abs, Sign, Range for all types.       //
 // NB: These functions are unfortunately not available in a portable    //
 // way in std::.                                                        //
 //                                                                      //
 // More functions are defined in TMath.h. TMathBase.h is designed to be //
 // a stable file and used in place of TMath.h in the ROOT miniCore.     //
 //                                                                      //
 //////////////////////////////////////////////////////////////////////////
 
 #include "RtypesCore.h"
 
 #include <cstdlib>
 #include <cmath>
 #include <algorithm>
 
 namespace TMath {
 
    // Abs
    inline Short_t  Abs(Short_t d);
    inline Int_t    Abs(Int_t d);
    inline Long_t   Abs(Long_t d);
    inline Long64_t Abs(Long64_t d);
    inline Float_t  Abs(Float_t d);
    inline Double_t Abs(Double_t d);
    inline LongDouble_t Abs(LongDouble_t d);
 
    // Even/Odd
    inline Bool_t   Even(Long_t a);
    inline Bool_t   Odd(Long_t a);
 
    // SignBit
    template<typename Integer>
    inline Bool_t SignBit(Integer a);
    inline Bool_t SignBit(Float_t a);
    inline Bool_t SignBit(Double_t a);
    inline Bool_t SignBit(LongDouble_t a);
 
    // Sign
    template<typename T1, typename T2>
    inline T1 Sign( T1 a, T2 b);
    inline Float_t  Sign(Float_t a, Float_t b);
    inline Double_t Sign(Double_t a, Double_t b);
    inline LongDouble_t Sign(LongDouble_t a, LongDouble_t b);
 
    // Min, Max of two scalars
    inline Short_t   Min(Short_t a, Short_t b);
    inline UShort_t  Min(UShort_t a, UShort_t b);
    inline Int_t     Min(Int_t a, Int_t b);
    inline UInt_t    Min(UInt_t a, UInt_t b);
    inline Long_t    Min(Long_t a, Long_t b);
    inline ULong_t   Min(ULong_t a, ULong_t b);
    inline Long64_t  Min(Long64_t a, Long64_t b);
    inline ULong64_t Min(ULong64_t a, ULong64_t b);
    inline Float_t   Min(Float_t a, Float_t b);
    inline Double_t  Min(Double_t a, Double_t b);
 
    inline Short_t   Max(Short_t a, Short_t b);
    inline UShort_t  Max(UShort_t a, UShort_t b);
    inline Int_t     Max(Int_t a, Int_t b);
    inline UInt_t    Max(UInt_t a, UInt_t b);
    inline Long_t    Max(Long_t a, Long_t b);
    inline ULong_t   Max(ULong_t a, ULong_t b);
    inline Long64_t  Max(Long64_t a, Long64_t b);
    inline ULong64_t Max(ULong64_t a, ULong64_t b);
    inline Float_t   Max(Float_t a, Float_t b);
    inline Double_t  Max(Double_t a, Double_t b);
 
    // Range
    inline Short_t   Range(Short_t lb, Short_t ub, Short_t x);
    inline Int_t     Range(Int_t lb, Int_t ub, Int_t x);
    inline Long_t    Range(Long_t lb, Long_t ub, Long_t x);
    inline ULong_t   Range(ULong_t lb, ULong_t ub, ULong_t x);
    inline Double_t  Range(Double_t lb, Double_t ub, Double_t x);
 
    //NextPrime is used by the Core classes.
    Long_t   NextPrime(Long_t x);   // Least prime number greater than x
 
    // Binary search
    template <typename T> Long64_t BinarySearch(Long64_t n, const T  *array, T value);
    template <typename T> Long64_t BinarySearch(Long64_t n, const T **array, T value);
    template <typename Iterator, typename Element> Iterator BinarySearch(Iterator first, Iterator last, Element value)
        R__DEPRECATED(6,40, "Undefined behavior in case \"value\" is smaller than the first element. Use STL algorithms instead, e.g. std::lower_bound(v.rbegin(), v.rend(), value, std::greater{}).");
 
    // Sorting
    template <typename Element, typename Index>
    void Sort(Index n, const Element* a, Index* index, Bool_t down=kTRUE);
    template <typename Iterator, typename IndexIterator>
    void SortItr(Iterator first, Iterator last, IndexIterator index, Bool_t down=kTRUE);
 }
 
 
 //---- Even/odd ----------------------------------------------------------------
 
 /// Returns `true` if `a` is even.
 inline Bool_t TMath::Even(Long_t a)
    { return ! (a & 1); }
 
 /// Returns `true` if `a` is odd.
 inline Bool_t TMath::Odd(Long_t a)
    { return (a & 1); }
 
 //---- Abs ---------------------------------------------------------------------
 
 /// Returns the absolute value of parameter `Short_t d`.
 inline Short_t TMath::Abs(Short_t d)
 { return (d >= 0) ? d : Short_t(-d);  }
 
 /// Returns the absolute value of parameter `Int_t d`.
 inline Int_t TMath::Abs(Int_t d)
 { return std::abs(d); }
 
 /// Returns the absolute value of parameter `Long_t d`.
 inline Long_t TMath::Abs(Long_t d)
 { return std::labs(d); }
 
 /// Returns the absolute value of parameter `Long64_t d`.
 inline Long64_t TMath::Abs(Long64_t d)
 { return std::llabs(d); }
 
 /// Returns the absolute value of parameter `Float_t d`.
 inline Float_t TMath::Abs(Float_t d)
 { return std::abs(d); }
 
 /// Returns the absolute value of parameter `Double_t d`.
 inline Double_t TMath::Abs(Double_t d)
 { return std::abs(d); }
 
 /// Returns the absolute value of parameter `LongDouble_t d`.
 inline LongDouble_t TMath::Abs(LongDouble_t d)
 { return std::abs(d); }
 
 
 //---- Sign Bit--------------------------------------------------------------------
 
 /// Returns whether the sign of `Integer a` is negative.
 template<typename Integer>
 inline Bool_t TMath::SignBit( Integer a)
    { return (a < 0); }
 
 /// Returns whether the sign of `Float_t a` is negative.
 inline Bool_t TMath::SignBit(Float_t a)
    { return std::signbit(a);  }
 
 /// Returns whether the sign of `Double_t a` is negative.
 inline Bool_t TMath::SignBit(Double_t a)
    { return std::signbit(a);  }
 
 /// Returns whether the sign of `LongDouble_t a` is negative.
 inline Bool_t TMath::SignBit(LongDouble_t a)
    { return std::signbit(a);  }
 
 
 //---- Sign --------------------------------------------------------------------
 
 /// Returns a value with the magnitude of `a` and the sign of `b`.
 template<typename T1, typename T2>
 inline T1 TMath::Sign( T1 a, T2 b)
    { return (SignBit(b)) ? - Abs(a) : Abs(a); }
 
 /// Returns a value with the magnitude of `a` and the sign of `b`.
 /// `a`and `b` are `Short_t`.
 inline Float_t TMath::Sign(Float_t a, Float_t b)
    { return std::copysign(a,b);  }
 
 /// Returns a value with the magnitude of `a` and the sign of `b`.
 /// `a`and `b` are `Double_t`.
 inline Double_t TMath::Sign(Double_t a, Double_t b)
    { return std::copysign(a,b);  }
 
 /// Returns a value with the magnitude of `a` and the sign of `b`.
 /// `a`and `b` are `LongDouble_t`.
 inline LongDouble_t TMath::Sign(LongDouble_t a, LongDouble_t b)
    { return std::copysign(a,b);  }
 
 
 //---- Min ---------------------------------------------------------------------
 
 /// Returns the smallest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Short_t`.
 inline Short_t TMath::Min(Short_t a, Short_t b)
    { return a <= b ? a : b; }
 
 /// Returns the smallest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `UShort_t`.
 inline UShort_t TMath::Min(UShort_t a, UShort_t b)
    { return a <= b ? a : b; }
 
 /// Returns the smallest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Int_t`.
 inline Int_t TMath::Min(Int_t a, Int_t b)
    { return a <= b ? a : b; }
 
 /// Returns the smallest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Short_t`.
 inline UInt_t TMath::Min(UInt_t a, UInt_t b)
    { return a <= b ? a : b; }
 
 /// Returns the smallest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Long_t`.
 inline Long_t TMath::Min(Long_t a, Long_t b)
    { return a <= b ? a : b; }
 
 /// Returns the smallest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `ULong_t`.
 inline ULong_t TMath::Min(ULong_t a, ULong_t b)
    { return a <= b ? a : b; }
 
 /// Returns the smallest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Long64_t`.
 inline Long64_t TMath::Min(Long64_t a, Long64_t b)
    { return a <= b ? a : b; }
 
 /// Returns the smallest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `ULong64_t`.
 inline ULong64_t TMath::Min(ULong64_t a, ULong64_t b)
    { return a <= b ? a : b; }
 
 /// Returns the smallest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Float_t`.
 inline Float_t TMath::Min(Float_t a, Float_t b)
    { return a <= b ? a : b; }
 
 /// Returns the smallest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Double_t`.
 inline Double_t TMath::Min(Double_t a, Double_t b)
    { return a <= b ? a : b; }
 
 //---- Max ---------------------------------------------------------------------
 
 /// Returns the largest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Short_t`.
 inline Short_t TMath::Max(Short_t a, Short_t b)
    { return a >= b ? a : b; }
 
 /// Returns the largest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `UShort_t`.
 inline UShort_t TMath::Max(UShort_t a, UShort_t b)
    { return a >= b ? a : b; }
 
 /// Returns the largest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Int_t`.
 inline Int_t TMath::Max(Int_t a, Int_t b)
    { return a >= b ? a : b; }
 
 /// Returns the largest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `UInt_t`.
 inline UInt_t TMath::Max(UInt_t a, UInt_t b)
    { return a >= b ? a : b; }
 
 /// Returns the largest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Long_t`.
 inline Long_t TMath::Max(Long_t a, Long_t b)
    { return a >= b ? a : b; }
 
 /// Returns the largest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `ULong_t`.
 inline ULong_t TMath::Max(ULong_t a, ULong_t b)
    { return a >= b ? a : b; }
 
 /// Returns the largest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Long64_t`.
 inline Long64_t TMath::Max(Long64_t a, Long64_t b)
    { return a >= b ? a : b; }
 
 /// Returns the largest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `ULong64_t`.
 inline ULong64_t TMath::Max(ULong64_t a, ULong64_t b)
    { return a >= b ? a : b; }
 
 /// Returns the largest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Float_t`.
 inline Float_t TMath::Max(Float_t a, Float_t b)
    { return a >= b ? a : b; }
 
 /// Returns the largest of `a` and `b`. If both are equivalent, `a` is returned.
 /// `a`and `b` are `Double_t`.
 inline Double_t TMath::Max(Double_t a, Double_t b)
    { return a >= b ? a : b; }
 
 //---- Range -------------------------------------------------------------------
 
 /// Returns `x` if `lb < x < up`, `lb` if `x < lb` and `ub` if `x > ub`.
 /// `lb`, `ub` and `x` are `Short_t`.
 inline Short_t TMath::Range(Short_t lb, Short_t ub, Short_t x)
    { return x < lb ? lb : (x > ub ? ub : x); }
 
 /// Returns `x` if `lb < x < up`, `lb` if `x < lb` and `ub` if `x > ub`.
 /// `lb`, `ub` and `x` are `Int_t`.
 inline Int_t TMath::Range(Int_t lb, Int_t ub, Int_t x)
    { return x < lb ? lb : (x > ub ? ub : x); }
 
 /// Returns `x` if `lb < x < up`, `lb` if `x < lb` and `ub` if `x > ub`.
 /// `lb`, `ub` and `x` are `Long_t`.
 inline Long_t TMath::Range(Long_t lb, Long_t ub, Long_t x)
    { return x < lb ? lb : (x > ub ? ub : x); }
 
 /// Returns `x` if `lb < x < up`, `lb` if `x < lb` and `ub` if `x > ub`.
 /// `lb`, `ub` and `x` are `ULong_t`.
 inline ULong_t TMath::Range(ULong_t lb, ULong_t ub, ULong_t x)
    { return x < lb ? lb : (x > ub ? ub : x); }
 
 /// Returns `x` if `lb < x < up`, `lb` if `x < lb` and `ub` if `x > ub`.
 /// `lb`, `ub` and `x` are `Double_t`.
 inline Double_t TMath::Range(Double_t lb, Double_t ub, Double_t x)
    { return x < lb ? lb : (x > ub ? ub : x); }
 
 /// Binary search in an array defined by its iterators.
 ///
 /// The values in the iterators range are supposed to be sorted
 /// prior to this call.  If match is found, function returns
 /// position of element.  If no match found, function gives nearest
 /// element smaller than value.
 template <typename Iterator, typename Element>
 Iterator TMath::BinarySearch(Iterator first, Iterator last, Element value)
 {
    Iterator pind;
    pind = std::lower_bound(first, last, value);
    if ( (pind != last) && (*pind == value) )
       return pind;
    else
       return ( pind - 1);
 }
 
 /// Binary search in an array of n values to locate value.
 ///
 /// Array is supposed  to be sorted prior to this call.
 /// If match is found, function returns position of element.
 /// If no match found, function gives nearest element smaller than value.
 template <typename T> Long64_t TMath::BinarySearch(Long64_t n, const T  *array, T value)
 {
    const T* pind;
    pind = std::lower_bound(array, array + n, value);
    if ( (pind != array + n) && (*pind == value) )
       return (pind - array);
    else
       return ( pind - array - 1);
 }
 
 /// Binary search in an array of n values to locate value.
 ///
 /// Array is supposed  to be sorted prior to this call.
 /// If match is found, function returns position of element.
 /// If no match found, function gives nearest element smaller than value.
 template <typename T> Long64_t TMath::BinarySearch(Long64_t n, const T **array, T value)
 {
    const T* pind;
    pind = std::lower_bound(*array, *array + n, value);
    if ( (pind != *array + n) && (*pind == value) )
       return (pind - *array);
    else
       return ( pind - *array - 1);
 }
 
 template<typename T>
 struct CompareDesc {
 
    CompareDesc(T d) : fData(d) {}
 
    template<typename Index>
    bool operator()(Index i1, Index i2) {
       return *(fData + i1) > *(fData + i2);
    }
 
    T fData;
 };
 
 template<typename T>
 struct CompareAsc {
 
    CompareAsc(T d) : fData(d) {}
 
    template<typename Index>
    bool operator()(Index i1, Index i2) {
       return *(fData + i1) < *(fData + i2);
    }
 
    T fData;
 };
 
 /// Sort the n1 elements of the Short_t array defined by its
 /// iterators.  In output the array index contains the indices of
 /// the sorted array.  If down is false sort in increasing order
 /// (default is decreasing order).
 ///
 /// NOTE that the array index must be created with a length bigger
 /// or equal than the main array before calling this function.
 template <typename Iterator, typename IndexIterator>
 void TMath::SortItr(Iterator first, Iterator last, IndexIterator index, Bool_t down)
 {
    int i = 0;
 
    IndexIterator cindex = index;
    for ( Iterator cfirst = first; cfirst != last; ++cfirst )
    {
       *cindex = i++;
       ++cindex;
    }
 
    if ( down )
       std::sort(index, cindex, CompareDesc<Iterator>(first) );
    else
       std::sort(index, cindex, CompareAsc<Iterator>(first) );
 }
 
 /// Sort the n elements of the  array a of generic templated type Element.
 /// In output the array index of type Index contains the indices of the sorted array.
 /// If down is false sort in increasing order (default is decreasing order).
 ///
 /// NOTE that the array index must be created with a length >= n
 /// before calling this function.
 /// NOTE also that the size type for n must be the same type used for the index array
 /// (templated type Index)
 template <typename Element, typename Index> void TMath::Sort(Index n, const Element* a, Index* index, Bool_t down)
 {
    for(Index i = 0; i < n; i++) { index[i] = i; }
    if ( down )
       std::sort(index, index + n, CompareDesc<const Element*>(a) );
    else
       std::sort(index, index + n, CompareAsc<const Element*>(a) );
 }
 
 #endif

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