PROGRAM subroutines
!
! Author:  Br. David Carlson
!
! Date:  April 2, 2008
!
! This program prompts the user for an angle in degrees, it then
! finds and prints the angle in radians, along with the original
! degrees.

IMPLICIT NONE

REAL::ThetaRadians
REAL::ThetaDegrees

CALL GetAngle(ThetaDegrees)
CALL DegreesToRadians(ThetaDegrees, ThetaRadians)
CALL Print(ThetaDegrees, ThetaRadians)

END PROGRAM


!----------------------------------------------------------------------
! Given:   Nothing.
! Task:    To have the user enter an angle in degrees.
! Return:  Angle    This angle entered by the user.
!----------------------------------------------------------------------
SUBROUTINE GetAngle(Angle)

IMPLICIT NONE

REAL, INTENT(OUT)::Angle

WRITE (*, *) 'Enter an angle (in degrees):'
READ (*, *) Angle

END SUBROUTINE


!----------------------------------------------------------------------
! Given:   ThetaDegrees     An angle in degrees.
! Task:    To find the size of this angle in radians.
! Return:  ThetaRadians     The computed size of the angle in radians.
!----------------------------------------------------------------------
SUBROUTINE DegreesToRadians(ThetaDegrees, ThetaRadians)

IMPLICIT NONE
REAL, INTENT(IN)::ThetaDegrees
REAL, INTENT(OUT)::ThetaRadians

! Local variable:
REAL::RadiansPerDegree

RadiansPerDegree = ASIN(1.0) / 90.0
ThetaRadians = ThetaDegrees * RadiansPerDegree

END SUBROUTINE


!----------------------------------------------------------------------
! Given:   ThetaDegrees     An angle in degrees.
!          ThetaRadians     The same angle in radians.
! Task:    To print these two values with appropriate messages.
! Return:  Nothing.
!----------------------------------------------------------------------
SUBROUTINE Print(ThetaDegrees, ThetaRadians)

IMPLICIT NONE
REAL, INTENT(IN)::ThetaDegrees, ThetaRadians

WRITE (*, 200) 'The angle in degrees is ', ThetaDegrees
WRITE (*, 200) 'The angle in radians is ', ThetaRadians

200 FORMAT(' ', A, F16.5)

END SUBROUTINE