! Adapted from http://www.aspire.cs.uah.edu/textbook/fortran8008.html
! This program allows the user to input the number of degrees in an angle
! and then computes the cosine, sine, and tangent. It continues until the
! user inputs "n" or "N".
      PROGRAM angle
      IMPLICIT none
! Type variables.
      REAL :: cosine, sine, tangent, degrees
      REAL :: pi = 3.141592
      CHARACTER :: choice
      DO
! Enter and read the number of degrees in the angle.
         PRINT *, "Enter the number of degrees in the angle."
         READ *, degrees
! Convert number of degrees in angle to radians.
         degrees = degrees*(pi/180)
! Use intrinsic functions to compute values.
         cosine=cos(degrees)
         sine=sin(degrees)
         tangent=tan(degrees)
! Print results.
        PRINT *, "cosine=", cosine, " sine=", sine, " tangent=", tangent
! Give user chance to exit program.
         PRINT *
         PRINT *, "Would you like to do this again?"
         PRINT *,"(Press n to exit - any other key to continue.)"
         READ *, choice
! Exit loop if the value in choice is N or n.
         IF (choice == "N" .or. choice == "n") EXIT
      END DO
      STOP
      END PROGRAM angle