spmpar Function

  function spmpar(i)

    !! Calculates machine (computing) parameters
    !! author: P J Knight, CCFE, Culham Science Centre
    !! i : input integer : Switch for return value:
    !! i=1 : B**(1 - P), the machine precision
    !! i=2 : B**(EMIN - 1), the smallest magnitude
    !! i=3 : B**EMAX*(1 - B**(-P)), the largest magnitude
    !! where the machine being used has P base B digits, and its smallest
    !! and largest exponents are EMIN and EMAX, respectively.
    !! This routine evaluates the numerical machine parameters of the
    !! computer being used to run the program, as defined above.
    !! <P>Note that the values of these parameters can be found for a given
    !! machine if the Mark 12 or later NAg library is installed on it.
    !! <P><CODE>SPMPAR(1)</CODE> is equivalent to <CODE>X02AJF()</CODE>;
    !! <BR><CODE>SPMPAR(2)</CODE> is equivalent to <CODE>X02AKF()</CODE>;
    !! <BR><CODE>SPMPAR(3)</CODE> is equivalent to <CODE>X02ALF()</CODE>.
    !! Metcalf and Reid, Fortran 90/95 Explained, 2nd Edition (section 8.7.2)
    !
    ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    implicit none

    real(dp) :: spmpar

    !  Arguments

    integer, intent(in) :: i

    !  Local variables

    real(dp), dimension(3) :: rmach

    ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    !  Previously-used hardwired values shown in comments

    !rmach(1) = 1.110223024625157D-016
    rmach(1) = epsilon(0.0D0)

    !rmach(2) = 2.3D-308
    rmach(2) = tiny(0.0D0)

    !rmach(3) = 1.797693134862316D+308
    rmach(3) = huge(0.0D0)

    spmpar = rmach(i)

  end function spmpar