logarithm.h

// Description: Logarithms
// Documentation: math_functions.txt

#ifndef PASTELSYS_LOGARITHM_H
#define PASTELSYS_LOGARITHM_H

#include "pastel/sys/integer/finite_integer_concept.h"
#include "pastel/sys/real/real_concept.h"

namespace Pastel
{

    //! Computes floor(log_2(x)).
    /*!
   Preconditions:
   x >= 1
   */
    template <typename Real>
    integer floorLog2(
        NoDeduction<Real> x);

    //! Computes the [base-2 logarithm] of x.
    /*!
   Preconditions:
   x >= 0
   */
    template <typename Real>
    Real log2(
        const NoDeduction<Real>& x);

    //! Returns floor(log_2(that)).
    /*!
   Time complexity:
   O(log(bits(that))),

   Preconditions:
   that > 0
   */
    template <typename Finite_Integer>
    integer integerLog2(const Finite_Integer& that);

    //! Returns ceil(log_2(that)).
    /*!
   Time complexity:
   O(log(bits(that))),

   Preconditions:
   that > 0
   */
    template <typename Finite_Integer>
    integer integerCeilLog2(const Finite_Integer& that);

}

#include "pastel/sys/math/logarithm.hpp"

#endif