! Example 2.8. Two assignments with mixed types.
  program C08
    implicit none
    real, parameter :: A = 3.0
    integer, parameter :: K = 3
    integer :: M1, M2
! start program C08
    M1 = (A / 4) * K  ! M1 = (3.0 / 4) * 3
    M2 = (K / 4) * A  ! M2 = (3 / 4) * 3.0
    write (unit = *, fmt = *) M1, M2
    stop
  end program C08

! Examples of intrinsic library functions.
  program C09
    implicit none
    real :: A, B, C, Term
! start program C09
    write (unit = *, fmt = *) atan2( 0.0, -1.0 ), exp( 1.0 )
    read (unit = *, fmt = *) A, B, C
    Term = sqrt( abs( B ** 2 - 4.0 * A * C ) )
    write (unit = *, fmt = *) A, B, C, Term
    stop
  end program C09

! Examples of intrinsic library functions.
  program C09
    implicit none
    real :: A, B, C, Term
! start program C09
    write (unit = *, fmt = *) atan2( 0.0, -1.0 ), exp( 1.0 )
    read (unit = *, fmt = *) A, B, C
    Term = sqrt( abs( B ** 2 - 4.0 * A * C ) )
    write (unit = *, fmt = *) A, B, C, Term
    stop
  end program C09

! Simple sort with module subroutine Swap.
  program C12
    use Swap_Reals_M
    implicit none
    real :: A, B, C
! start program C12
    write (unit = *, fmt = *) " Please enter three numbers."
    read (unit = *, fmt = *) A, B, C
    write (unit = *, fmt = *) " Thank you. You have entered: ", A, B, C
    if (A > B) then
      call Swap( A, B )
    end if
    if (A > C) then
      call Swap( A, C )
    end if
    if (B > C) then
      call Swap( B, C )
    end if
    write (unit = *, fmt = *) " The numbers in increasing order are: ", A, B, C
    stop
  end program C12




! Temperature Conversion with Subroutines.
  program C13
    use C13M
    implicit none
    real :: Fahr, Cels
! start program C13
    call Input( Fahr )
    call Calculate( Fahr, Cels )
    call Output( Fahr, Cels )
    stop
  end program C13
! Program Example from "Essential Fortran 90 & 95" by Loren P. Meissner
! Copyright 1996. Copying for sale requires permission from the author.
! Otherwise, distribution is permitted if these three lines are included.

  module C13M
    implicit none
    public :: Input, Calculate, Output
  contains
    subroutine Input( FT1 )
      real, intent (out) :: FT1
  ! start subroutine Input
      write (unit = *, fmt = *) " Please enter the Fahrenheit temperature. "
      read (unit = *, fmt = *) FT1
      return
    end subroutine Input
    subroutine Calculate (FT2, CT2)
      real, intent (in) :: FT2
      real, intent (out) :: CT2
    real, parameter :: T_SCALE = 1.8, OFFSET = 32.0
  ! start subroutine Calculate
      CT2 = (FT2 - OFFSET) / T_SCALE
      return
    end subroutine Calculate
    subroutine Output( FT3, CT3 )
      real, intent (in) :: FT3, CT3
  ! start subroutine Output
      write (unit = *, fmt = *) FT3, " deg. F = ", CT3, " deg. C"
      return
    end subroutine Output
  end module C13M

  program C3X12
    implicit none
    real, parameter :: A = 16.0, B = 4.0, C = 0.25, Theta = -0.5, X = 4.0
    integer, parameter :: I = 1, J = -256, L = 4, M = 17, N = 8, Minute = 61
! start program C3X12
    write (unit = *, fmt = *) abs( A ) * B / C
    write (unit = *, fmt = *) sqrt( real( ((M - 9) / L) * N ) )
    write (unit = *, fmt = *) A * sign( Theta, 1.0 )
    write (unit = *, fmt = *) 0.5 * (sqrt( X ) + A / sqrt( X ))
    write (unit = *, fmt = *) abs( I - 5 )
    write (unit = *, fmt = *) modulo( Minute, 60 )
    write (unit = *, fmt = *) max( abs( I - 5 ), I, 1 )
    write (unit = *, fmt = *) sqrt( sqrt( A ) )
    write (unit = *, fmt = *) sqrt( B ** 2 - 4.0 * A * C ) / (2.0 * A)
    write (unit = *, fmt = *) 1 + nint( sqrt( real( abs( J ) ) ) )
    stop
  end program C3X12


    module calculations
       public :: mean, geomean, standev
    contains
       subroutine mean(x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,mv)
          real,intent(in) :: x1,x2,x3,x4,x5,x6,x7,x8,x9,x10
          real, intent(out) :: mv
          real :: s
          s=x1+x2+x3+x4+x5+x6+x7+x8+x9+x10
          mv=s/10
       end subroutine mean
       subroutine geomean(x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,gm)
          real, intent(in) :: x1,x2,x3,x4,x5,x6,x7,x8,x9,x10
          real, intent(out) :: gm
          real :: m
          m=x1*x2*x3*x4*x5*x6*x7*x8*x9*x10
          gm=exp(log(m)/10)
       end subroutine geomean
       subroutine standev(x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,mv,sd)
          real, intent(in) :: x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,mv
          real, intent(out) :: sd
          real :: u
          u=(x1-mv)**2+(x2-mv)**2+(x3-mv)**2+(x4-mv)**2
          u=u+(x5-mv)**2+(x6-mv)**2+(x7-mv)**2+(x8-mv)**2
          u=u+(x9-mv)**2+(x10-mv)**2
          sd=sqrt(u/(10-1))
       end subroutine standev
    end module calculations