;      FUNCTION DIFF(K,J)
FUNCTION diff,j
;
;       NOTE: The single parameter to the IDL function is the
;	satellite number 6..12.
;
;C                         ADDED TO CODE:  25 AUG 1992
;      SAVE
;      CHARACTER*3 J
;      DIMENSION DIFF6(40),DIFF7(40),DIFF8(40),DIFF9(40)
;      DIMENSION DIFF10(40),DIFF11(40),DIFF12(40)
;C
;      DATA NCALL/0/
COMMON diffstuff,ncall,diff6,diff7,diff8,diff9,diff10,diff11,diff12
;C
;      IF(NCALL.EQ.0) THEN
IF NOT ncall THEN BEGIN
    ncall=1B
;	NCALL=1
;	DO 10 I=1,40
;	  DIFF6(I)=1./(GEOMF(I,' F6')*.098)
    diff6=1./(geomf(6)*0.098)
;	  DIFF7(I)=1./(GEOMF(I,' F7')*.098)
    diff7=1./(geomf(7)*0.098)
;	  DIFF8(I)=1./(GEOMF(I,' F8')*.098)
    diff8=1./(geomf(8)*0.098)
;	  DIFF9(I)=1./(GEOMF(I,' F9')*.098)
    diff9=1./(geomf(9)*0.098)
;	  DIFF10(I)=1./(GEOMF(I,'F10')*.098)
    diff10=1./(geomf(10)*0.098)
;	  DIFF11(I)=1./(GEOMF(I,'F11')*.098)
    diff11=1./(geomf(11)*0.098)
;	  DIFF12(I)=1./(GEOMF(I,'F12')*.098)
    diff12=1./(geomf(12)*0.098)
;  10    CONTINUE
;      ENDIF
    ENDIF
;C
;      DIFF=-1
diffp=REPLICATE(-1.,40)
;      IF(K.LT.1.OR.K.GT.40) RETURN
;C
;      IF(J.EQ.' F6') THEN
;	DIFF=DIFF6(K)
;      ELSE IF(J.EQ.' F7') THEN
;	DIFF=DIFF7(K)
;      ELSE IF(J.EQ.' F8') THEN
;	DIFF=DIFF8(K)
;      ELSE IF(J.EQ.' F9') THEN
;	DIFF=DIFF9(K)
;      ELSE IF(J.EQ.'F10') THEN
;	DIFF=DIFF10(K)
;      ELSE IF(J.EQ.'F11') THEN
;	DIFF=DIFF11(K)
;      ELSE IF(J.EQ.'F12') THEN
;	DIFF=DIFF12(K)
;      ENDIF
CASE j OF
 6: diffp=diff6
 7: diffp=diff7
 8: diffp=diff8
 9: diffp=diff9
10: diffp=diff10
11: diffp=diff11
12: diffp=diff12
ELSE:
    ENDCASE
;C
;      RETURN
;      END
RETURN,diffp
END