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zunk1.f
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zunk1.f
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SUBROUTINE ZUNK1(ZR, ZI, FNU, KODE, MR, N, YR, YI, NZ, TOL, ELIM,
* ALIM)
C***BEGIN PROLOGUE ZUNK1
C***REFER TO ZBESK
C
C ZUNK1 COMPUTES K(FNU,Z) AND ITS ANALYTIC CONTINUATION FROM THE
C RIGHT HALF PLANE TO THE LEFT HALF PLANE BY MEANS OF THE
C UNIFORM ASYMPTOTIC EXPANSION.
C MR INDICATES THE DIRECTION OF ROTATION FOR ANALYTIC CONTINUATION.
C NZ=-1 MEANS AN OVERFLOW WILL OCCUR
C
C***ROUTINES CALLED ZKSCL,ZS1S2,ZUCHK,ZUNIK,D1MACH,ZABS
C***END PROLOGUE ZUNK1
C COMPLEX CFN,CK,CONE,CRSC,CS,CSCL,CSGN,CSPN,CSR,CSS,CWRK,CY,CZERO,
C *C1,C2,PHI,PHID,RZ,SUM,SUMD,S1,S2,Y,Z,ZETA1,ZETA1D,ZETA2,ZETA2D,ZR
DOUBLE PRECISION ALIM, ANG, APHI, ASC, ASCLE, BRY, CKI, CKR,
* CONER, CRSC, CSCL, CSGNI, CSPNI, CSPNR, CSR, CSRR, CSSR,
* CWRKI, CWRKR, CYI, CYR, C1I, C1R, C2I, C2M, C2R, ELIM, FMR, FN,
* FNF, FNU, PHIDI, PHIDR, PHII, PHIR, PI, RAST, RAZR, RS1, RZI,
* RZR, SGN, STI, STR, SUMDI, SUMDR, SUMI, SUMR, S1I, S1R, S2I,
* S2R, TOL, YI, YR, ZEROI, ZEROR, ZETA1I, ZETA1R, ZETA2I, ZETA2R,
* ZET1DI, ZET1DR, ZET2DI, ZET2DR, ZI, ZR, ZRI, ZRR, D1MACH, ZABS
INTEGER I, IB, IFLAG, IFN, IL, INIT, INU, IUF, K, KDFLG, KFLAG,
* KK, KODE, MR, N, NW, NZ, INITD, IC, IPARD, J
DIMENSION BRY(3), INIT(2), YR(N), YI(N), SUMR(2), SUMI(2),
* ZETA1R(2), ZETA1I(2), ZETA2R(2), ZETA2I(2), CYR(2), CYI(2),
* CWRKR(16,3), CWRKI(16,3), CSSR(3), CSRR(3), PHIR(2), PHII(2)
DATA ZEROR,ZEROI,CONER / 0.0D0, 0.0D0, 1.0D0 /
DATA PI / 3.14159265358979324D0 /
C
KDFLG = 1
NZ = 0
C-----------------------------------------------------------------------
C EXP(-ALIM)=EXP(-ELIM)/TOL=APPROX. ONE PRECISION GREATER THAN
C THE UNDERFLOW LIMIT
C-----------------------------------------------------------------------
CSCL = 1.0D0/TOL
CRSC = TOL
CSSR(1) = CSCL
CSSR(2) = CONER
CSSR(3) = CRSC
CSRR(1) = CRSC
CSRR(2) = CONER
CSRR(3) = CSCL
BRY(1) = 1.0D+3*D1MACH(1)/TOL
BRY(2) = 1.0D0/BRY(1)
BRY(3) = D1MACH(2)
ZRR = ZR
ZRI = ZI
IF (ZR.GE.0.0D0) GO TO 10
ZRR = -ZR
ZRI = -ZI
10 CONTINUE
J = 2
DO 70 I=1,N
C-----------------------------------------------------------------------
C J FLIP FLOPS BETWEEN 1 AND 2 IN J = 3 - J
C-----------------------------------------------------------------------
J = 3 - J
FN = FNU + DBLE(FLOAT(I-1))
INIT(J) = 0
CALL ZUNIK(ZRR, ZRI, FN, 2, 0, TOL, INIT(J), PHIR(J), PHII(J),
* ZETA1R(J), ZETA1I(J), ZETA2R(J), ZETA2I(J), SUMR(J), SUMI(J),
* CWRKR(1,J), CWRKI(1,J))
IF (KODE.EQ.1) GO TO 20
STR = ZRR + ZETA2R(J)
STI = ZRI + ZETA2I(J)
RAST = FN/ZABS(COMPLEX(STR,STI))
STR = STR*RAST*RAST
STI = -STI*RAST*RAST
S1R = ZETA1R(J) - STR
S1I = ZETA1I(J) - STI
GO TO 30
20 CONTINUE
S1R = ZETA1R(J) - ZETA2R(J)
S1I = ZETA1I(J) - ZETA2I(J)
30 CONTINUE
RS1 = S1R
C-----------------------------------------------------------------------
C TEST FOR UNDERFLOW AND OVERFLOW
C-----------------------------------------------------------------------
IF (DABS(RS1).GT.ELIM) GO TO 60
IF (KDFLG.EQ.1) KFLAG = 2
IF (DABS(RS1).LT.ALIM) GO TO 40
C-----------------------------------------------------------------------
C REFINE TEST AND SCALE
C-----------------------------------------------------------------------
APHI = ZABS(COMPLEX(PHIR(J),PHII(J)))
RS1 = RS1 + DLOG(APHI)
IF (DABS(RS1).GT.ELIM) GO TO 60
IF (KDFLG.EQ.1) KFLAG = 1
IF (RS1.LT.0.0D0) GO TO 40
IF (KDFLG.EQ.1) KFLAG = 3
40 CONTINUE
C-----------------------------------------------------------------------
C SCALE S1 TO KEEP INTERMEDIATE ARITHMETIC ON SCALE NEAR
C EXPONENT EXTREMES
C-----------------------------------------------------------------------
S2R = PHIR(J)*SUMR(J) - PHII(J)*SUMI(J)
S2I = PHIR(J)*SUMI(J) + PHII(J)*SUMR(J)
STR = DEXP(S1R)*CSSR(KFLAG)
S1R = STR*DCOS(S1I)
S1I = STR*DSIN(S1I)
STR = S2R*S1R - S2I*S1I
S2I = S1R*S2I + S2R*S1I
S2R = STR
IF (KFLAG.NE.1) GO TO 50
CALL ZUCHK(S2R, S2I, NW, BRY(1), TOL)
IF (NW.NE.0) GO TO 60
50 CONTINUE
CYR(KDFLG) = S2R
CYI(KDFLG) = S2I
YR(I) = S2R*CSRR(KFLAG)
YI(I) = S2I*CSRR(KFLAG)
IF (KDFLG.EQ.2) GO TO 75
KDFLG = 2
GO TO 70
60 CONTINUE
IF (RS1.GT.0.0D0) GO TO 300
C-----------------------------------------------------------------------
C FOR ZR.LT.0.0, THE I FUNCTION TO BE ADDED WILL OVERFLOW
C-----------------------------------------------------------------------
IF (ZR.LT.0.0D0) GO TO 300
KDFLG = 1
YR(I)=ZEROR
YI(I)=ZEROI
NZ=NZ+1
IF (I.EQ.1) GO TO 70
IF ((YR(I-1).EQ.ZEROR).AND.(YI(I-1).EQ.ZEROI)) GO TO 70
YR(I-1)=ZEROR
YI(I-1)=ZEROI
NZ=NZ+1
70 CONTINUE
I = N
75 CONTINUE
RAZR = 1.0D0/ZABS(COMPLEX(ZRR,ZRI))
STR = ZRR*RAZR
STI = -ZRI*RAZR
RZR = (STR+STR)*RAZR
RZI = (STI+STI)*RAZR
CKR = FN*RZR
CKI = FN*RZI
IB = I + 1
IF (N.LT.IB) GO TO 160
C-----------------------------------------------------------------------
C TEST LAST MEMBER FOR UNDERFLOW AND OVERFLOW. SET SEQUENCE TO ZERO
C ON UNDERFLOW.
C-----------------------------------------------------------------------
FN = FNU + DBLE(FLOAT(N-1))
IPARD = 1
IF (MR.NE.0) IPARD = 0
INITD = 0
CALL ZUNIK(ZRR, ZRI, FN, 2, IPARD, TOL, INITD, PHIDR, PHIDI,
* ZET1DR, ZET1DI, ZET2DR, ZET2DI, SUMDR, SUMDI, CWRKR(1,3),
* CWRKI(1,3))
IF (KODE.EQ.1) GO TO 80
STR = ZRR + ZET2DR
STI = ZRI + ZET2DI
RAST = FN/ZABS(COMPLEX(STR,STI))
STR = STR*RAST*RAST
STI = -STI*RAST*RAST
S1R = ZET1DR - STR
S1I = ZET1DI - STI
GO TO 90
80 CONTINUE
S1R = ZET1DR - ZET2DR
S1I = ZET1DI - ZET2DI
90 CONTINUE
RS1 = S1R
IF (DABS(RS1).GT.ELIM) GO TO 95
IF (DABS(RS1).LT.ALIM) GO TO 100
C----------------------------------------------------------------------------
C REFINE ESTIMATE AND TEST
C-------------------------------------------------------------------------
APHI = ZABS(COMPLEX(PHIDR,PHIDI))
RS1 = RS1+DLOG(APHI)
IF (DABS(RS1).LT.ELIM) GO TO 100
95 CONTINUE
IF (DABS(RS1).GT.0.0D0) GO TO 300
C-----------------------------------------------------------------------
C FOR ZR.LT.0.0, THE I FUNCTION TO BE ADDED WILL OVERFLOW
C-----------------------------------------------------------------------
IF (ZR.LT.0.0D0) GO TO 300
NZ = N
DO 96 I=1,N
YR(I) = ZEROR
YI(I) = ZEROI
96 CONTINUE
RETURN
C---------------------------------------------------------------------------
C FORWARD RECUR FOR REMAINDER OF THE SEQUENCE
C----------------------------------------------------------------------------
100 CONTINUE
S1R = CYR(1)
S1I = CYI(1)
S2R = CYR(2)
S2I = CYI(2)
C1R = CSRR(KFLAG)
ASCLE = BRY(KFLAG)
DO 120 I=IB,N
C2R = S2R
C2I = S2I
S2R = CKR*C2R - CKI*C2I + S1R
S2I = CKR*C2I + CKI*C2R + S1I
S1R = C2R
S1I = C2I
CKR = CKR + RZR
CKI = CKI + RZI
C2R = S2R*C1R
C2I = S2I*C1R
YR(I) = C2R
YI(I) = C2I
IF (KFLAG.GE.3) GO TO 120
STR = DABS(C2R)
STI = DABS(C2I)
C2M = DMAX1(STR,STI)
IF (C2M.LE.ASCLE) GO TO 120
KFLAG = KFLAG + 1
ASCLE = BRY(KFLAG)
S1R = S1R*C1R
S1I = S1I*C1R
S2R = C2R
S2I = C2I
S1R = S1R*CSSR(KFLAG)
S1I = S1I*CSSR(KFLAG)
S2R = S2R*CSSR(KFLAG)
S2I = S2I*CSSR(KFLAG)
C1R = CSRR(KFLAG)
120 CONTINUE
160 CONTINUE
IF (MR.EQ.0) RETURN
C-----------------------------------------------------------------------
C ANALYTIC CONTINUATION FOR RE(Z).LT.0.0D0
C-----------------------------------------------------------------------
NZ = 0
FMR = DBLE(FLOAT(MR))
SGN = -DSIGN(PI,FMR)
C-----------------------------------------------------------------------
C CSPN AND CSGN ARE COEFF OF K AND I FUNCTIONS RESP.
C-----------------------------------------------------------------------
CSGNI = SGN
INU = INT(SNGL(FNU))
FNF = FNU - DBLE(FLOAT(INU))
IFN = INU + N - 1
ANG = FNF*SGN
CSPNR = DCOS(ANG)
CSPNI = DSIN(ANG)
IF (MOD(IFN,2).EQ.0) GO TO 170
CSPNR = -CSPNR
CSPNI = -CSPNI
170 CONTINUE
ASC = BRY(1)
IUF = 0
KK = N
KDFLG = 1
IB = IB - 1
IC = IB - 1
DO 270 K=1,N
FN = FNU + DBLE(FLOAT(KK-1))
C-----------------------------------------------------------------------
C LOGIC TO SORT OUT CASES WHOSE PARAMETERS WERE SET FOR THE K
C FUNCTION ABOVE
C-----------------------------------------------------------------------
M=3
IF (N.GT.2) GO TO 175
172 CONTINUE
INITD = INIT(J)
PHIDR = PHIR(J)
PHIDI = PHII(J)
ZET1DR = ZETA1R(J)
ZET1DI = ZETA1I(J)
ZET2DR = ZETA2R(J)
ZET2DI = ZETA2I(J)
SUMDR = SUMR(J)
SUMDI = SUMI(J)
M = J
J = 3 - J
GO TO 180
175 CONTINUE
IF ((KK.EQ.N).AND.(IB.LT.N)) GO TO 180
IF ((KK.EQ.IB).OR.(KK.EQ.IC)) GO TO 172
INITD = 0
180 CONTINUE
CALL ZUNIK(ZRR, ZRI, FN, 1, 0, TOL, INITD, PHIDR, PHIDI,
* ZET1DR, ZET1DI, ZET2DR, ZET2DI, SUMDR, SUMDI,
* CWRKR(1,M), CWRKI(1,M))
IF (KODE.EQ.1) GO TO 200
STR = ZRR + ZET2DR
STI = ZRI + ZET2DI
RAST = FN/ZABS(COMPLEX(STR,STI))
STR = STR*RAST*RAST
STI = -STI*RAST*RAST
S1R = -ZET1DR + STR
S1I = -ZET1DI + STI
GO TO 210
200 CONTINUE
S1R = -ZET1DR + ZET2DR
S1I = -ZET1DI + ZET2DI
210 CONTINUE
C-----------------------------------------------------------------------
C TEST FOR UNDERFLOW AND OVERFLOW
C-----------------------------------------------------------------------
RS1 = S1R
IF (DABS(RS1).GT.ELIM) GO TO 260
IF (KDFLG.EQ.1) IFLAG = 2
IF (DABS(RS1).LT.ALIM) GO TO 220
C-----------------------------------------------------------------------
C REFINE TEST AND SCALE
C-----------------------------------------------------------------------
APHI = ZABS(COMPLEX(PHIDR,PHIDI))
RS1 = RS1 + DLOG(APHI)
IF (DABS(RS1).GT.ELIM) GO TO 260
IF (KDFLG.EQ.1) IFLAG = 1
IF (RS1.LT.0.0D0) GO TO 220
IF (KDFLG.EQ.1) IFLAG = 3
220 CONTINUE
STR = PHIDR*SUMDR - PHIDI*SUMDI
STI = PHIDR*SUMDI + PHIDI*SUMDR
S2R = -CSGNI*STI
S2I = CSGNI*STR
STR = DEXP(S1R)*CSSR(IFLAG)
S1R = STR*DCOS(S1I)
S1I = STR*DSIN(S1I)
STR = S2R*S1R - S2I*S1I
S2I = S2R*S1I + S2I*S1R
S2R = STR
IF (IFLAG.NE.1) GO TO 230
CALL ZUCHK(S2R, S2I, NW, BRY(1), TOL)
IF (NW.EQ.0) GO TO 230
S2R = ZEROR
S2I = ZEROI
230 CONTINUE
CYR(KDFLG) = S2R
CYI(KDFLG) = S2I
C2R = S2R
C2I = S2I
S2R = S2R*CSRR(IFLAG)
S2I = S2I*CSRR(IFLAG)
C-----------------------------------------------------------------------
C ADD I AND K FUNCTIONS, K SEQUENCE IN Y(I), I=1,N
C-----------------------------------------------------------------------
S1R = YR(KK)
S1I = YI(KK)
IF (KODE.EQ.1) GO TO 250
CALL ZS1S2(ZRR, ZRI, S1R, S1I, S2R, S2I, NW, ASC, ALIM, IUF)
NZ = NZ + NW
250 CONTINUE
YR(KK) = S1R*CSPNR - S1I*CSPNI + S2R
YI(KK) = CSPNR*S1I + CSPNI*S1R + S2I
KK = KK - 1
CSPNR = -CSPNR
CSPNI = -CSPNI
IF (C2R.NE.0.0D0 .OR. C2I.NE.0.0D0) GO TO 255
KDFLG = 1
GO TO 270
255 CONTINUE
IF (KDFLG.EQ.2) GO TO 275
KDFLG = 2
GO TO 270
260 CONTINUE
IF (RS1.GT.0.0D0) GO TO 300
S2R = ZEROR
S2I = ZEROI
GO TO 230
270 CONTINUE
K = N
275 CONTINUE
IL = N - K
IF (IL.EQ.0) RETURN
C-----------------------------------------------------------------------
C RECUR BACKWARD FOR REMAINDER OF I SEQUENCE AND ADD IN THE
C K FUNCTIONS, SCALING THE I SEQUENCE DURING RECURRENCE TO KEEP
C INTERMEDIATE ARITHMETIC ON SCALE NEAR EXPONENT EXTREMES.
C-----------------------------------------------------------------------
S1R = CYR(1)
S1I = CYI(1)
S2R = CYR(2)
S2I = CYI(2)
CSR = CSRR(IFLAG)
ASCLE = BRY(IFLAG)
FN = DBLE(FLOAT(INU+IL))
DO 290 I=1,IL
C2R = S2R
C2I = S2I
S2R = S1R + (FN+FNF)*(RZR*C2R-RZI*C2I)
S2I = S1I + (FN+FNF)*(RZR*C2I+RZI*C2R)
S1R = C2R
S1I = C2I
FN = FN - 1.0D0
C2R = S2R*CSR
C2I = S2I*CSR
CKR = C2R
CKI = C2I
C1R = YR(KK)
C1I = YI(KK)
IF (KODE.EQ.1) GO TO 280
CALL ZS1S2(ZRR, ZRI, C1R, C1I, C2R, C2I, NW, ASC, ALIM, IUF)
NZ = NZ + NW
280 CONTINUE
YR(KK) = C1R*CSPNR - C1I*CSPNI + C2R
YI(KK) = C1R*CSPNI + C1I*CSPNR + C2I
KK = KK - 1
CSPNR = -CSPNR
CSPNI = -CSPNI
IF (IFLAG.GE.3) GO TO 290
C2R = DABS(CKR)
C2I = DABS(CKI)
C2M = DMAX1(C2R,C2I)
IF (C2M.LE.ASCLE) GO TO 290
IFLAG = IFLAG + 1
ASCLE = BRY(IFLAG)
S1R = S1R*CSR
S1I = S1I*CSR
S2R = CKR
S2I = CKI
S1R = S1R*CSSR(IFLAG)
S1I = S1I*CSSR(IFLAG)
S2R = S2R*CSSR(IFLAG)
S2I = S2I*CSSR(IFLAG)
CSR = CSRR(IFLAG)
290 CONTINUE
RETURN
300 CONTINUE
NZ = -1
RETURN
END