30 lines
873 B
Fortran
30 lines
873 B
Fortran
DOUBLE PRECISION FUNCTION AZABS(ZR, ZI)
|
|
C***BEGIN PROLOGUE AZABS
|
|
C***REFER TO ZBESH,ZBESI,ZBESJ,ZBESK,ZBESY,ZAIRY,ZBIRY
|
|
C
|
|
C AZABS COMPUTES THE ABSOLUTE VALUE OR MAGNITUDE OF A DOUBLE
|
|
C PRECISION COMPLEX VARIABLE CMPLX(ZR,ZI)
|
|
C
|
|
C***ROUTINES CALLED (NONE)
|
|
C***END PROLOGUE AZABS
|
|
DOUBLE PRECISION ZR, ZI, U, V, Q, S
|
|
U = DABS(ZR)
|
|
V = DABS(ZI)
|
|
S = U + V
|
|
C-----------------------------------------------------------------------
|
|
C S*1.0D0 MAKES AN UNNORMALIZED UNDERFLOW ON CDC MACHINES INTO A
|
|
C TRUE FLOATING ZERO
|
|
C-----------------------------------------------------------------------
|
|
S = S*1.0D+0
|
|
IF (S.EQ.0.0D+0) GO TO 20
|
|
IF (U.GT.V) GO TO 10
|
|
Q = U/V
|
|
AZABS = V*DSQRT(1.D+0+Q*Q)
|
|
RETURN
|
|
10 Q = V/U
|
|
AZABS = U*DSQRT(1.D+0+Q*Q)
|
|
RETURN
|
|
20 AZABS = 0.0D+0
|
|
RETURN
|
|
END
|