Mercurial > octave-nkf
view libcruft/amos/cuchk.f @ 15902:858cbf6fc2ec stable rc-3-6-4-1
Bump version for 3.6.4-rc1
author | John W. Eaton <jwe@octave.org> |
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date | Sat, 05 Jan 2013 19:46:27 -0500 |
parents | 82be108cc558 |
children |
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SUBROUTINE CUCHK(Y, NZ, ASCLE, TOL) C***BEGIN PROLOGUE CUCHK C***REFER TO CSERI,CUOIK,CUNK1,CUNK2,CUNI1,CUNI2,CKSCL C C Y ENTERS AS A SCALED QUANTITY WHOSE MAGNITUDE IS GREATER THAN C EXP(-ALIM)=ASCLE=1.0E+3*R1MACH(1)/TOL. THE TEST IS MADE TO SEE C IF THE MAGNITUDE OF THE REAL OR IMAGINARY PART WOULD UNDER FLOW C WHEN Y IS SCALED (BY TOL) TO ITS PROPER VALUE. Y IS ACCEPTED C IF THE UNDERFLOW IS AT LEAST ONE PRECISION BELOW THE MAGNITUDE C OF THE LARGEST COMPONENT; OTHERWISE THE PHASE ANGLE DOES NOT HAVE C ABSOLUTE ACCURACY AND AN UNDERFLOW IS ASSUMED. C C***ROUTINES CALLED (NONE) C***END PROLOGUE CUCHK C COMPLEX Y REAL ASCLE, SS, ST, TOL, YR, YI INTEGER NZ NZ = 0 YR = REAL(Y) YI = AIMAG(Y) YR = ABS(YR) YI = ABS(YI) ST = AMIN1(YR,YI) IF (ST.GT.ASCLE) RETURN SS = AMAX1(YR,YI) ST=ST/TOL IF (SS.LT.ST) NZ = 1 RETURN END