*DECK ZUCHK SUBROUTINE ZUCHK (YR, YI, NZ, ASCLE, TOL) C***BEGIN PROLOGUE ZUCHK C***SUBSIDIARY C***PURPOSE Subsidiary to SERI, ZUOIK, ZUNK1, ZUNK2, ZUNI1, ZUNI2 and C ZKSCL C***LIBRARY SLATEC C***TYPE ALL (CUCHK-A, ZUCHK-A) C***AUTHOR Amos, D. E., (SNL) C***DESCRIPTION C C Y ENTERS AS A SCALED QUANTITY WHOSE MAGNITUDE IS GREATER THAN C EXP(-ALIM)=ASCLE=1.0E+3*D1MACH(1)/TOL. THE TEST IS MADE TO SEE C IF THE MAGNITUDE OF THE REAL OR IMAGINARY PART WOULD UNDERFLOW 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***SEE ALSO SERI, ZKSCL, ZUNI1, ZUNI2, ZUNK1, ZUNK2, ZUOIK C***ROUTINES CALLED (NONE) C***REVISION HISTORY (YYMMDD) C ?????? DATE WRITTEN C 910415 Prologue converted to Version 4.0 format. (BAB) C***END PROLOGUE ZUCHK C C COMPLEX Y DOUBLE PRECISION ASCLE, SS, ST, TOL, WR, WI, YR, YI INTEGER NZ C***FIRST EXECUTABLE STATEMENT ZUCHK NZ = 0 WR = ABS(YR) WI = ABS(YI) ST = MIN(WR,WI) IF (ST.GT.ASCLE) RETURN SS = MAX(WR,WI) ST = ST/TOL IF (SS.LT.ST) NZ = 1 RETURN END