kind_parameters.f90

!> Numerical storage size parameters for real and integer values
!> See https://fortran-lang.org/learn/best_practices/floating_point/
module kind_parameters

    implicit none(type, external)
    private

    !> Single precision real numbers, 6 digits, range 10⁻³⁷ to 10³⁷-1; 32 bits
    integer, parameter, public :: sp = selected_real_kind(6, 37)
    !> Double precision real numbers, 15 digits, range 10⁻³⁰⁷ to 10³⁰⁷-1; 64 bits
    integer, parameter, public :: dp = selected_real_kind(15, 307)
    !> Quadruple precision real numbers, 33 digits, range 10⁻⁴⁹³¹ to 10⁴⁹³¹-1; 128 bits
    integer, parameter, public :: qp = selected_real_kind(33, 4931)

    !> Char length for integers, range -2⁷ to 2⁷-1; 8 bits
    integer, parameter, public :: i1 = selected_int_kind(2)
    !> Short length for integers, range -2¹⁵ to 2¹⁵-1; 16 bits
    integer, parameter, public :: i2 = selected_int_kind(4)
    !> Length of default integers, range -2³¹ to 2³¹-1; 32 bits
    integer, parameter, public :: i4 = selected_int_kind(9)
    !> Long length for integers, range -2⁶³ to 2⁶³-1; 64 bits
    integer, parameter, public :: i8 = selected_int_kind(18)

end module kind_parameters