Mercurial > octave
view libcruft/amos/xzabs.f @ 4960:ce01dbd7e026 ss-2-1-58
[project @ 2004-09-02 03:47:49 by jwe]
author | jwe |
---|---|
date | Thu, 02 Sep 2004 03:47:49 +0000 |
parents | 8b0cb8f79fdc |
children |
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DOUBLE PRECISION FUNCTION XZABS(ZR, ZI) C***BEGIN PROLOGUE XZABS C***REFER TO ZBESH,ZBESI,ZBESJ,ZBESK,ZBESY,ZAIRY,ZBIRY C C XZABS COMPUTES THE ABSOLUTE VALUE OR MAGNITUDE OF A DOUBLE C PRECISION COMPLEX VARIABLE CMPLX(ZR,ZI) C C***ROUTINES CALLED (NONE) C***END PROLOGUE XZABS 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 XZABS = V*DSQRT(1.D+0+Q*Q) RETURN 10 Q = V/U XZABS = U*DSQRT(1.D+0+Q*Q) RETURN 20 XZABS = 0.0D+0 RETURN END