MODULE trig
! the following are simple trigometric functions with
! arguments in degrees - they exit are intrinsic functions
! on Compact (Didital) compliers and so are not needed.
! However they are not part of standard fortran95.
IMPLICIT NONE

PUBLIC :: SIN_D, COS_D, TAN_D, ASIN_D, ACOS_D, ATAN_D, ATAN2_D
PRIVATE :: SIND4, COSD4, TAND4, ASIND4, ACOSD4, ATAND4, ATAN2d4
PRIVATE :: SIND8, COSD8, TAND8, ASIND8, ACOSD8, ATAND8, ATAN2d8


REAL (KIND=4), PARAMETER, PRIVATE :: pi4 = 3.141592653589793238_4
REAL (KIND=8), PARAMETER, PRIVATE :: pi8 = 3.141592653589793238_8


INTERFACE SIN_D
    MODULE PROCEDURE SIND4,SIND8
END INTERFACE SIN_D

INTERFACE COS_D
    MODULE PROCEDURE COSD4,COSD8
END INTERFACE COS_D

INTERFACE TAN_D
    MODULE PROCEDURE TAND4,TAND8
END INTERFACE TAN_D

INTERFACE ASIN_D
    MODULE PROCEDURE ASIND4,ASIND8
END INTERFACE ASIN_D

INTERFACE ACOS_D
    MODULE PROCEDURE ACOSD4,ACOSD8
END INTERFACE ACOS_D

INTERFACE ATAN_D
    MODULE PROCEDURE ATAND4,ATAND8
END INTERFACE ATAN_D

INTERFACE ATAN2_D
    MODULE PROCEDURE ATAN2D4,ATAN2D8
END INTERFACE ATAN2_D


CONTAINS
    ELEMENTAL FUNCTION SIND4(theta) RESULT(funct_out)
    REAL (kind=4),INTENT(IN) :: theta 
    REAL (KIND=4) :: funct_out
    funct_out = SIN(theta*pi4/180.0)
    RETURN
    END FUNCTION SIND4

    ELEMENTAL FUNCTION SIND8(theta) RESULT(funct_out)
    REAL (kind=8),INTENT(IN) :: theta 
    REAL (KIND=8) :: funct_out

    funct_out = SIN(theta*pi8/180.0)
    RETURN
    END FUNCTION SIND8

!CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
    ELEMENTAL FUNCTION COSD4(theta) RESULT(funct_out)
    REAL (kind=4),INTENT(IN) :: theta 
    REAL (KIND=4) :: funct_out


    funct_out = COS(theta*pi4/180.0)
    RETURN
    END FUNCTION COSD4

    ELEMENTAL FUNCTION COSD8(theta) RESULT(funct_out)
    REAL (kind=8),INTENT(IN) :: theta 
    REAL (KIND=8) :: funct_out

    funct_out = COS(theta*pi8/180.0)
    RETURN
    END FUNCTION COSD8

!CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC     
    ELEMENTAL  FUNCTION TAND4(theta) RESULT(funct_out)
    REAL (kind=4), INTENT(IN) :: theta 
    REAL (KIND=4) :: funct_out
     
    funct_out = TAN(theta*pi4/180.0)
     
    RETURN
    END FUNCTION TAND4

    ELEMENTAL  FUNCTION TAND8(theta) RESULT(funct_out)
    REAL (kind=8), INTENT(IN) :: theta 
    REAL (KIND=8) :: funct_out
     
    funct_out = TAN(theta*pi8/180.0)
     
    RETURN
    END FUNCTION TAND8
!CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
    ELEMENTAL FUNCTION ASIND4(x) RESULT(funct_out)
    REAL (kind=4), INTENT(IN) :: x 
    REAL (KIND=4) :: funct_out
     
    funct_out = ASIN(x)*180.0/pi4
     
    RETURN
    END FUNCTION ASIND4

    ELEMENTAL FUNCTION ASIND8(x) RESULT(funct_out)
    REAL (kind=8), INTENT(IN) :: x 
    REAL (KIND=8) :: funct_out
     
    funct_out = ASIN(x)*180.0/pi8
     
    RETURN
    END FUNCTION ASIND8

!CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
    ELEMENTAL FUNCTION ACOSD4(x) RESULT(funct_out)
    REAL (kind=4), INTENT(IN) :: x 
    REAL (KIND=4) :: funct_out
     
    funct_out = ACOS(x)*180.0/pi4
     
    RETURN
    END FUNCTION ACOSD4

    ELEMENTAL FUNCTION ACOSD8(x) RESULT(funct_out)
    REAL (kind=8), INTENT(IN) :: x 
    REAL (KIND=8) :: funct_out
     
    funct_out = ACOS(x)*180.0/pi8
     
    RETURN
    END FUNCTION ACOSD8
!CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
    ELEMENTAL FUNCTION ATAND4(x) RESULT(funct_out)
    REAL (kind=4), INTENT(IN) :: x 
    REAL (KIND=4) :: funct_out
     
    funct_out = ATAN(x)*180.0/pi4
     
    RETURN
    END FUNCTION ATAND4

    ELEMENTAL FUNCTION ATAND8(x) RESULT(funct_out)
    REAL (kind=8), INTENT(IN) :: x 
    REAL (KIND=8) :: funct_out
     
    funct_out = ATAN(x)*180.0/pi8
     
    RETURN
    END FUNCTION ATAND8
!CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
    ELEMENTAL FUNCTION ATAN2D4(x,y) RESULT(funct_out)
    REAL (kind=4), INTENT(IN) :: x,y 
    REAL (KIND=4) :: funct_out
  
    IF (x == 0.0 .AND. y == 0.0) THEN
        funct_out = 0.0
        RETURN
    END IF      
    funct_out = ATAN2(x,y)*180.0/pi4
    RETURN
    END FUNCTION ATAN2D4
  
    ELEMENTAL FUNCTION ATAN2D8(x,y) RESULT(funct_out)
    REAL (kind=8), INTENT(IN) :: x,y 
    REAL (KIND=8) :: funct_out
 
    IF (x == 0.0 .AND. y == 0.0) THEN
        funct_out = 0.0
        RETURN
    END IF      
    funct_out = ATAN2(x,y)*180.0/pi8
    RETURN
    END FUNCTION ATAN2D8
    END MODULE trig