mirror of
https://git.planet-casio.com/Lephenixnoir/OpenLibm.git
synced 2025-01-01 06:23:39 +01:00
77 lines
2.3 KiB
Fortran
77 lines
2.3 KiB
Fortran
*DECK XADJ
|
|
SUBROUTINE XADJ (X, IX, IERROR)
|
|
C***BEGIN PROLOGUE XADJ
|
|
C***PURPOSE To provide single-precision floating-point arithmetic
|
|
C with an extended exponent range.
|
|
C***LIBRARY SLATEC
|
|
C***CATEGORY A3D
|
|
C***TYPE SINGLE PRECISION (XADJ-S, DXADJ-D)
|
|
C***KEYWORDS EXTENDED-RANGE SINGLE-PRECISION ARITHMETIC
|
|
C***AUTHOR Lozier, Daniel W., (National Bureau of Standards)
|
|
C Smith, John M., (NBS and George Mason University)
|
|
C***DESCRIPTION
|
|
C REAL X
|
|
C INTEGER IX
|
|
C
|
|
C TRANSFORMS (X,IX) SO THAT
|
|
C RADIX**(-L) .LE. ABS(X) .LT. RADIX**L.
|
|
C ON MOST COMPUTERS THIS TRANSFORMATION DOES
|
|
C NOT CHANGE THE MANTISSA OF X PROVIDED RADIX IS
|
|
C THE NUMBER BASE OF SINGLE-PRECISION ARITHMETIC.
|
|
C
|
|
C***SEE ALSO XSET
|
|
C***REFERENCES (NONE)
|
|
C***ROUTINES CALLED XERMSG
|
|
C***COMMON BLOCKS XBLK2
|
|
C***REVISION HISTORY (YYMMDD)
|
|
C 820712 DATE WRITTEN
|
|
C 881020 Revised to meet SLATEC CML recommendations. (DWL and JMS)
|
|
C 901019 Revisions to prologue. (DWL and WRB)
|
|
C 901106 Changed all specific intrinsics to generic. (WRB)
|
|
C Corrected order of sections in prologue and added TYPE
|
|
C section. (WRB)
|
|
C CALLs to XERROR changed to CALLs to XERMSG. (WRB)
|
|
C 920127 Revised PURPOSE section of prologue. (DWL)
|
|
C***END PROLOGUE XADJ
|
|
REAL X
|
|
INTEGER IX
|
|
REAL RADIX, RADIXL, RAD2L, DLG10R
|
|
INTEGER L, L2, KMAX
|
|
COMMON /XBLK2/ RADIX, RADIXL, RAD2L, DLG10R, L, L2, KMAX
|
|
SAVE /XBLK2/
|
|
C
|
|
C THE CONDITION IMPOSED ON L AND KMAX BY THIS SUBROUTINE
|
|
C IS
|
|
C 2*L .LE. KMAX
|
|
C
|
|
C THIS CONDITION MUST BE MET BY APPROPRIATE CODING
|
|
C IN SUBROUTINE XSET.
|
|
C
|
|
C***FIRST EXECUTABLE STATEMENT XADJ
|
|
IERROR=0
|
|
IF (X.EQ.0.0) GO TO 50
|
|
IF (ABS(X).GE.1.0) GO TO 20
|
|
IF (RADIXL*ABS(X).GE.1.0) GO TO 60
|
|
X = X*RAD2L
|
|
IF (IX.LT.0) GO TO 10
|
|
IX = IX - L2
|
|
GO TO 70
|
|
10 IF (IX.LT.-KMAX+L2) GO TO 40
|
|
IX = IX - L2
|
|
GO TO 70
|
|
20 IF (ABS(X).LT.RADIXL) GO TO 60
|
|
X = X/RAD2L
|
|
IF (IX.GT.0) GO TO 30
|
|
IX = IX + L2
|
|
GO TO 70
|
|
30 IF (IX.GT.KMAX-L2) GO TO 40
|
|
IX = IX + L2
|
|
GO TO 70
|
|
40 CALL XERMSG ('SLATEC', 'XADJ', 'overflow in auxiliary index', 107,
|
|
+ 1)
|
|
IERROR=107
|
|
RETURN
|
|
50 IX = 0
|
|
60 IF (ABS(IX).GT.KMAX) GO TO 40
|
|
70 RETURN
|
|
END
|