C     SccsID = "@(#)akspec.f	1.1     07/23/03"
      SUBROUTINE AKSPEC (ICODE,NZN,FLAT,FLON,X,Y,CC,S)
      IMPLICIT REAL*8 (A-H,O-Z)
      CHARACTER*4 IGP,IPC,ICODE
      DIMENSION C29(9),CM(9)
      DATA C29/6*5.0D5,7.0D5,5.0D5,6.0D5/,CM/2*5.112D5,5.256D5,5.4D5,
     *  5.544D5,5.688D5,5.832D5,5.976D5,6.12D5/
      DATA B/1.00029977273D0/,C/4.47599131D-3/,D/6.38635267013D6/,
     *  F/0.327015517176D0/,G/0.945018968871D0/,H/0.3460412203D0/,
     *  T/6.8147849D-3/,E/8.2271854223003D-2/,EE/2.718281828459045D0/,
     *  PI/3.14159265358979D0/,RHOSEC/2.06264806247D5/
      DATA IPC/'PCGP'/
      IF (ICODE.EQ.IPC) GO TO 20
      COSP=DCOS(FLAT)
      SINP=DSIN(FLAT)
      IF (NZN.GT.1) GO TO 10
C   ALASKA, ZONE 1
      C2=DSQRT(1.D0-E*E*SINP*SINP)
      BDL=B*(FLON-1.7717540856301D0)
      SNBDL=DSIN(BDL)
      CSBDL=DCOS(BDL)
      BUC=B*(DLOG(DTAN(PI/4.D0+FLAT/2.D0))
     *  -E/2.D0*DLOG((1.D0+E*SINP)/(1.D0-E*SINP)))+ C
      EP=EE**BUC
      EN=EE**(-BUC)
      P=0.5D0*(EP-EN)
      Q=0.5D0*(EP+EN)
      U=D*DATAN((G*P+F*SNBDL)/CSBDL)
      V=D/2.D0*DLOG((Q+F*P-G*SNBDL)/(Q-F*P+G*SNBDL))
      X=3.28083333333D0*(5.D6-0.6D0*U+0.8D0*V)
      Y=3.28083333333D0*(0.6D0*V+0.8D0*U-5.D6)
      CC=DATAN((3.D0*Q*CSBDL-4.D0*P*SNBDL-4.D0*H)/
     *       (4.D0*Q*CSBDL+3.D0*P*SNBDL+3.D0*H))
      S=1.0015773595D0*C2*DCOS(U/D)/COSP/CSBDL
      RETURN
C   ALASKA, ZONE 2-9
   10 CONTINUE
      DLON=(CM(NZN)-FLON*RHOSEC)/1.D4
      DLON2=DLON*DLON
      DLON4=DLON2*DLON2
      COSP2=COSP*COSP
      COSP4=COSP2*COSP2
      COSP6=COSP4*COSP2
      S2=DSQRT(1.D0+T*COSP2)
      S3=DSQRT(1.D0-COSP2)*COSP
      X=C29(NZN)+1.01786215D6*COSP/S2*DLON*(1.D0-3.91740509D-4*DLON2*
     *    (1.D0-2.D0*COSP2-T*COSP4)+4.60382D-8*DLON4*(1.D0-20.D0*COSP2+
     *    23.6047D0*COSP4+0.4907D0*COSP6))
      Y=101.269278503D0*(FLAT*RHOSEC-1.9390005442D5-(1.052893943D3-
     *    4.483386D0*COSP2+2.3599D-2*COSP4)*S3)+2.46736748D4*S3/S2*DLON2
     *    *(1.D0+1.958703D-4*DLON2*(-1.D0+6.D0*COSP2+6.133306D-2*COSP4+
     *    1.8577D-4*COSP6)+1.5346D-8*DLON4*(1.D0-60.D0*COSP2+
     *    117.75D0*COSP4+4.089D0*COSP6))
      CC=S3/COSP*DLON*(1.D4+7.83481D0*DLON2*(COSP2+2.044D-2*COSP4
     *    +0.9D-4*COSP6)+0.3683D-2*DLON4*(3.D0*COSP4-COSP2))/RHOSEC
      S=0.9999D0*(1.D0+S2**4/8.81572821D2*((X-C29(NZN))/1.D6)**2)
      RETURN
   20 CONTINUE
      IF (NZN.GT.1) GO TO 30
C   ALASKA, ZONE 1
      U=-0.182880365761D00*X+0.243840487681D00*Y +7.D06
      V=0.243840487681D00*X +0.182880365761D0*Y -1.D06
      FAR=V/D
      EP=EE**FAR
      EM=EE**(-FAR)
      R=(EP-EM)/2.D0
      S=(EP+EM)/2.D0
      SINUD=DSIN(U/D)
      COSUD=DCOS(U/D)
      GSUD=G*SINUD
      EM=EE**(DLOG((S+F*R+GSUD)/(S-F*R-GSUD))/(2.D0*B)-C/B)
      XR=2.D0*DATAN(EM)-PI/2.D0
      SINXR=DSIN(XR)
      COSXR=DCOS(XR)
      COSXR2=COSXR*COSXR
      FLAT=XR+SINXR*COSXR*(6.761032571D-3 +COSXR2*(5.3172205D-5 +
     1 COSXR2*(5.73027D-7 +COSXR2*7.128D-9)))
      FLON=1.7717540856301D0+DATAN((F*SINUD-G*R)/COSUD)/B
      RETURN
C   ALASKA, ZONE 2-9
   30 CONTINUE
      O1SEC=1.93900054420D05 +9.87466302498D-3*Y
      COSO1=DCOS(O1SEC/RHOSEC)
      COSO12=COSO1*COSO1
      SINO1=DSIN(O1SEC/RHOSEC)
      P1SEC=O1SEC+SINO1*COSO1*(1.047546691D3+COSO12*(6.193011D0 +
     *  5.0699D-2*COSO12))
      COSP1=DCOS(P1SEC/RHOSEC)
      COSP12=COSP1*COSP1
      COSP14=COSP12*COSP12
      TANP1=DTAN(P1SEC/RHOSEC)
      TANP12=TANP1*TANP1
      W=1.D0+T*COSP12
      W2=W*W
      FAR=(X-C29(NZN))*1.D-6
      FAR2=FAR*FAR
      FAR4=FAR2*FAR2
      PSEC=P1SEC-2.33973645D2*FAR2*W2*TANP1*(1.D0-1.8905604D-4*FAR2*
     *  (1.9591113D0+3.D0/COSP12+8.1359D-2*COSP12+2.79D-4*COSP14)+
     *  1.42969D-8*FAR4*W*(15.5D0+45.D0/COSP14-0.307D0/COSP12+
     *  1.53D0*COSP12))
      ESEC=CM(NZN)-9.824513072D3*DSQRT(W)/COSP1*FAR*(1.D0-3.7811208D-4*W
     *  *FAR2*(2.D0*TANP12+W)+4.2890624D-8*W2*FAR4*(1.054D0+24.D0/COSP14
     *  -20.D0/COSP12-1.36D-2*COSP12))
      FLAT=PSEC/RHOSEC
      FLON=ESEC/RHOSEC
      RETURN
      END