PROGRAM astesti
  IMPLICIT NONE
  INTRINSIC ASIN, ACOS, ATAN
  WRITE (*,*) 'arcsin(0.5): ', asteina(ASIN,0.5)
  WRITE (*,*) 'arccos(0.5): ', asteina(ACOS,0.5)
  WRITE (*,*) 'arctan(1.0): ', asteina(ATAN,1.0)
CONTAINS
  REAL FUNCTION asteina(f, x)
    IMPLICIT NONE
    REAL, EXTERNAL :: f
    REAL :: x
    INTRINSIC ATAN
    asteina = 45*f(x)/ATAN(1.0)
  END FUNCTION asteina
END PROGRAM astesti