15bf364e5e
commit dbca224ee15f598ba86b860c19e902b594f6b888
Author: Jordan Sherer <jordan@widefido.com>
Date: Wed Aug 14 21:10:17 2019 -0400
Cleanup decoder with easy parameters
commit 427a6ac6bf02a7de80e76b921bbd48ec23dab0c4
Author: Jordan Sherer <jordan@widefido.com>
Date: Tue Aug 13 22:56:32 2019 -0400
Working on downsampling
commit ef5e1fb9cdafb6069b6f67377c3bc9e073d2785e
Author: Jordan Sherer <jordan@widefido.com>
Date: Tue Aug 13 22:01:34 2019 -0400
Fixed NN parameters
commit 216dbc83a931127540fb028d3365a205b4ef1d28
Author: Jordan Sherer <jordan@widefido.com>
Date: Tue Aug 13 21:40:20 2019 -0400
Fixed dupe during sync
commit 9505d50ba6c42b05e5fff1a059864a643d9e7558
Author: Jordan Sherer <jordan@widefido.com>
Date: Tue Aug 13 16:54:37 2019 -0400
Tweaking downsampling
commit 86cd07e1ac8ce8d64cdd2d4321cf295cd867f80e
Author: Jordan Sherer <jordan@widefido.com>
Date: Tue Aug 13 10:11:07 2019 -0400
Working with logging
commit 0de3849a442d20081f545c6fef5fadf2def6e0d2
Author: Jordan Sherer <jordan@widefido.com>
Date: Tue Aug 13 03:46:51 2019 -0400
250 millisecond startup delay
commit a35cc5302b6f8532a424d504a4e2feaacf74ef99
Author: Jordan Sherer <jordan@widefido.com>
Date: Tue Aug 13 03:39:20 2019 -0400
1200 sps, 10 seconds, 80Hz
commit 6f36db20f90c510336b497605d9d7667d6f0f44f
Author: Jordan Sherer <jordan@widefido.com>
Date: Tue Aug 13 03:27:12 2019 -0400
Working word count
commit 741c55ac0840512d68e1fbdb2f1fff6adfcd4612
Author: Jordan Sherer <jordan@widefido.com>
Date: Tue Aug 13 02:40:40 2019 -0400
Updated LDPC simulator
commit ce0992644315402503f44bdae4131bacf2cc3e21
Author: Jordan Sherer <jordan@widefido.com>
Date: Tue Aug 13 02:34:01 2019 -0400
Weird. Apparently symbol stop is the only way to get decodes to work in app...need to figure out why
commit 8b330fbff6574f2ee6d7a471dd93a2cb57b492dd
Author: Jordan Sherer <jordan@widefido.com>
Date: Tue Aug 13 01:50:37 2019 -0400
More parameter fixups (downsampling) and first decode
commit 37c780b45e6579294b5a4692b8e8d0602d9bd8b1
Author: Jordan Sherer <jordan@widefido.com>
Date: Mon Aug 12 23:20:58 2019 -0400
More params fixing
commit bc8547e1e8f55bfb4bce5f95890f3cf6798e36d7
Author: Jordan Sherer <jordan@widefido.com>
Date: Mon Aug 12 22:48:00 2019 -0400
Fixed params in fortran code
commit 10fbf9f4a78c6244e0082a31819ee26aeae39325
Author: Jordan Sherer <jordan@widefido.com>
Date: Mon Aug 12 16:08:32 2019 -0400
Using constants in place of literals in a few places to make it easier to change
458 lines
13 KiB
Fortran
458 lines
13 KiB
Fortran
subroutine ft8b(dd0,newdat,nQSOProgress,nfqso,nftx,ndepth,lapon,lapcqonly, &
|
|
napwid,lsubtract,nagain,iaptype,mycall12,mygrid6,hiscall12,bcontest, &
|
|
sync0,f1,xdt,xbase,apsym,nharderrors,dmin,nbadcrc,ipass,iera,msg37,xsnr)
|
|
|
|
use crc
|
|
use timer_module, only: timer
|
|
include 'ft8_params.f90'
|
|
parameter(NP2=2812)
|
|
character*37 msg37
|
|
character message*22,msgsent*22,origmsg*22
|
|
character*12 mycall12,hiscall12
|
|
character*6 mycall6,mygrid6,hiscall6,c1,c2
|
|
character*87 cbits
|
|
logical bcontest
|
|
real a(5)
|
|
real s1(0:7,ND),s2(0:7,NN),s1sort(8*ND)
|
|
real ps(0:7),psl(0:7)
|
|
real bmeta(3*ND),bmetb(3*ND),bmetap(3*ND)
|
|
real llr(3*ND),llra(3*ND),llr0(3*ND),llr1(3*ND),llrap(3*ND) !Soft symbols
|
|
real dd0(NMAX)
|
|
integer*1 decoded(KK),decoded0(KK),apmask(3*ND),cw(3*ND)
|
|
integer*1 msgbits(KK)
|
|
integer apsym(KK)
|
|
integer mcq(28),mde(28),mrrr(16),m73(16),mrr73(16)
|
|
integer itone(NN)
|
|
integer indxs1(8*ND)
|
|
integer icos7(0:6),ip(1)
|
|
integer nappasses(0:5) !Number of decoding passes to use for each QSO state
|
|
integer naptypes(0:5,4) ! (nQSOProgress, decoding pass) maximum of 4 passes for now
|
|
integer*1, target:: i1hiscall(12)
|
|
complex cd0(0:3199)
|
|
complex ctwk(NDOWNSPS)
|
|
complex csymb(NDOWNSPS)
|
|
logical first,newdat,lsubtract,lapon,lapcqonly,nagain
|
|
equivalence (s1,s1sort)
|
|
data icos7/4,2,5,6,1,3,0/
|
|
data mcq/1,1,1,1,1,0,1,0,0,0,0,0,1,0,0,0,0,0,1,1,0,0,0,1,1,0,0,1/
|
|
data mrrr/0,1,1,1,1,1,1,0,1,1,0,0,1,1,1,1/
|
|
data m73/0,1,1,1,1,1,1,0,1,1,0,1,0,0,0,0/
|
|
data mde/1,1,1,1,1,1,1,1,0,1,1,0,0,1,0,0,0,0,0,1,1,1,0,1,0,0,0,1/
|
|
data mrr73/0,0,0,0,0,0,1,0,0,0,0,1,0,1,0,1/
|
|
data first/.true./
|
|
save nappasses,naptypes
|
|
|
|
if(first) then
|
|
mcq=2*mcq-1
|
|
mde=2*mde-1
|
|
mrrr=2*mrrr-1
|
|
m73=2*m73-1
|
|
mrr73=2*mrr73-1
|
|
nappasses(0)=2
|
|
nappasses(1)=2
|
|
nappasses(2)=2
|
|
nappasses(3)=4
|
|
nappasses(4)=4
|
|
nappasses(5)=3
|
|
|
|
! iaptype
|
|
!------------------------
|
|
! 1 CQ ??? ???
|
|
! 2 MyCall ??? ???
|
|
! 3 MyCall DxCall ???
|
|
! 4 MyCall DxCall RRR
|
|
! 5 MyCall DxCall 73
|
|
! 6 MyCall DxCall RR73
|
|
! 7 ??? DxCall ???
|
|
|
|
naptypes(0,1:4)=(/1,2,0,0/)
|
|
naptypes(1,1:4)=(/2,3,0,0/)
|
|
naptypes(2,1:4)=(/2,3,0,0/)
|
|
naptypes(3,1:4)=(/3,4,5,6/)
|
|
naptypes(4,1:4)=(/3,4,5,6/)
|
|
naptypes(5,1:4)=(/3,1,2,0/)
|
|
first=.false.
|
|
endif
|
|
|
|
max_iterations=30
|
|
nharderrors=-1
|
|
fs2=12000.0/NDOWN
|
|
dt2=1.0/fs2
|
|
twopi=8.0*atan(1.0)
|
|
delfbest=0.
|
|
ibest=0
|
|
|
|
call timer('ft8_down',0)
|
|
call ft8_downsample(dd0,newdat,f1,cd0) !Mix f1 to baseband and downsample
|
|
call timer('ft8_down',1)
|
|
|
|
i0=nint((xdt+0.5)*fs2) !Initial guess for start of signal
|
|
smax=0.0
|
|
do idt=i0-8,i0+8 !Search over +/- one quarter symbol
|
|
call sync8d(cd0,idt,ctwk,0,sync)
|
|
if(sync.gt.smax) then
|
|
smax=sync
|
|
ibest=idt
|
|
endif
|
|
enddo
|
|
xdt2=ibest*dt2 !Improved estimate for DT
|
|
|
|
! Now peak up in frequency
|
|
i0=nint(xdt2*fs2)
|
|
smax=0.0
|
|
do ifr=-5,5 !Search over +/- 2.5 Hz
|
|
delf=ifr*0.5
|
|
dphi=twopi*delf*dt2
|
|
phi=0.0
|
|
do i=1,NDOWNSPS
|
|
ctwk(i)=cmplx(cos(phi),sin(phi))
|
|
phi=mod(phi+dphi,twopi)
|
|
enddo
|
|
call sync8d(cd0,i0,ctwk,1,sync)
|
|
if( sync .gt. smax ) then
|
|
smax=sync
|
|
delfbest=delf
|
|
endif
|
|
enddo
|
|
a=0.0
|
|
a(1)=-delfbest
|
|
call twkfreq1(cd0,NP2,fs2,a,cd0)
|
|
xdt=xdt2
|
|
f1=f1+delfbest !Improved estimate of DF
|
|
|
|
call sync8d(cd0,i0,ctwk,2,sync)
|
|
|
|
j=0
|
|
do k=1,NN
|
|
i1=ibest+(k-1)*NDOWNSPS
|
|
csymb=cmplx(0.0,0.0)
|
|
!if( i1.ge.1 .and. i1+31 .le. NP2 ) csymb=cd0(i1:i1+31)
|
|
if( i1.ge.0 .and. i1+(NDOWNSPS-1) .le. NP2-1 ) csymb=cd0(i1:i1+(NDOWNSPS-1))
|
|
call four2a(csymb,NDOWNSPS,1,-1,1)
|
|
s2(0:7,k)=abs(csymb(1:8))/1e3
|
|
enddo
|
|
|
|
! sync quality check
|
|
is1=0
|
|
is2=0
|
|
is3=0
|
|
do k=1,7
|
|
ip=maxloc(s2(:,k))
|
|
if(icos7(k-1).eq.(ip(1)-1)) is1=is1+1
|
|
ip=maxloc(s2(:,k+36))
|
|
if(icos7(k-1).eq.(ip(1)-1)) is2=is2+1
|
|
ip=maxloc(s2(:,k+72))
|
|
if(icos7(k-1).eq.(ip(1)-1)) is3=is3+1
|
|
enddo
|
|
! hard sync sum - max is 21
|
|
nsync=is1+is2+is3
|
|
|
|
! debug
|
|
!open(99, file="./js8.log", status="old", position="append", action="write")
|
|
!write(99,*) ibest, nsync
|
|
!close(99)
|
|
|
|
if(nsync .le. 6) then ! bail out
|
|
call timer('badnsync', 0)
|
|
nbadcrc=1
|
|
call timer('badnsync', 1)
|
|
return
|
|
endif
|
|
|
|
j=0
|
|
do k=1,NN
|
|
if(k.le.7) cycle
|
|
if(k.ge.37 .and. k.le.43) cycle
|
|
if(k.gt.72) cycle
|
|
j=j+1
|
|
s1(0:7,j)=s2(0:7,k)
|
|
enddo
|
|
|
|
call indexx(s1sort,8*ND,indxs1)
|
|
xmeds1=s1sort(indxs1(nint(0.5*8*ND)))
|
|
s1=s1/xmeds1
|
|
|
|
do j=1,ND
|
|
i4=3*j-2
|
|
i2=3*j-1
|
|
i1=3*j
|
|
! Max amplitude
|
|
ps=s1(0:7,j)
|
|
r1=max(ps(1),ps(3),ps(5),ps(7))-max(ps(0),ps(2),ps(4),ps(6))
|
|
r2=max(ps(2),ps(3),ps(6),ps(7))-max(ps(0),ps(1),ps(4),ps(5))
|
|
r4=max(ps(4),ps(5),ps(6),ps(7))-max(ps(0),ps(1),ps(2),ps(3))
|
|
bmeta(i4)=r4
|
|
bmeta(i2)=r2
|
|
bmeta(i1)=r1
|
|
bmetap(i4)=r4
|
|
bmetap(i2)=r2
|
|
bmetap(i1)=r1
|
|
! Max log metric
|
|
psl=log(ps+1e-32)
|
|
r1=max(psl(1),psl(3),psl(5),psl(7))-max(psl(0),psl(2),psl(4),psl(6))
|
|
r2=max(psl(2),psl(3),psl(6),psl(7))-max(psl(0),psl(1),psl(4),psl(5))
|
|
r4=max(psl(4),psl(5),psl(6),psl(7))-max(psl(0),psl(1),psl(2),psl(3))
|
|
bmetb(i4)=r4
|
|
bmetb(i2)=r2
|
|
bmetb(i1)=r1
|
|
|
|
! Metric for Cauchy noise
|
|
! r1=log(ps(1)**3+ps(3)**3+ps(5)**3+ps(7)**3)- &
|
|
! log(ps(0)**3+ps(2)**3+ps(4)**3+ps(6)**3)
|
|
! r2=log(ps(2)**3+ps(3)**3+ps(6)**3+ps(7)**3)- &
|
|
! log(ps(0)**3+ps(1)**3+ps(4)**3+ps(5)**3)
|
|
! r4=log(ps(4)**3+ps(5)**3+ps(6)**3+ps(7)**3)- &
|
|
! log(ps(0)**3+ps(1)**3+ps(2)**3+ps(3)**3)
|
|
! Metric for AWGN, no fading
|
|
! bscale=2.5
|
|
! b0=bessi0(bscale*ps(0))
|
|
! b1=bessi0(bscale*ps(1))
|
|
! b2=bessi0(bscale*ps(2))
|
|
! b3=bessi0(bscale*ps(3))
|
|
! b4=bessi0(bscale*ps(4))
|
|
! b5=bessi0(bscale*ps(5))
|
|
! b6=bessi0(bscale*ps(6))
|
|
! b7=bessi0(bscale*ps(7))
|
|
! r1=log(b1+b3+b5+b7)-log(b0+b2+b4+b6)
|
|
! r2=log(b2+b3+b6+b7)-log(b0+b1+b4+b5)
|
|
! r4=log(b4+b5+b6+b7)-log(b0+b1+b2+b3)
|
|
|
|
if(nQSOProgress .eq. 0 .or. nQSOProgress .eq. 5) then
|
|
! When bits 88:115 are set as ap bits, bit 115 lives in symbol 39 along
|
|
! with no-ap bits 116 and 117. Take care of metrics for bits 116 and 117.
|
|
if(j.eq.39) then ! take care of bits that live in symbol 39
|
|
if(apsym(28).lt.0) then
|
|
bmetap(i2)=max(ps(2),ps(3))-max(ps(0),ps(1))
|
|
bmetap(i1)=max(ps(1),ps(3))-max(ps(0),ps(2))
|
|
else
|
|
bmetap(i2)=max(ps(6),ps(7))-max(ps(4),ps(5))
|
|
bmetap(i1)=max(ps(5),ps(7))-max(ps(4),ps(6))
|
|
endif
|
|
endif
|
|
endif
|
|
|
|
! When bits 116:143 are set as ap bits, bit 115 lives in symbol 39 along
|
|
! with ap bits 116 and 117. Take care of metric for bit 115.
|
|
! if(j.eq.39) then ! take care of bit 115
|
|
! iii=2*(apsym(29)+1)/2 + (apsym(30)+1)/2 ! known values of bits 116 & 117
|
|
! if(iii.eq.0) bmetap(i4)=ps(4)-ps(0)
|
|
! if(iii.eq.1) bmetap(i4)=ps(5)-ps(1)
|
|
! if(iii.eq.2) bmetap(i4)=ps(6)-ps(2)
|
|
! if(iii.eq.3) bmetap(i4)=ps(7)-ps(3)
|
|
! endif
|
|
|
|
! bit 144 lives in symbol 48 and will be 1 if it is set as an ap bit.
|
|
! take care of metrics for bits 142 and 143
|
|
if(j.eq.48) then ! bit 144 is always 1
|
|
bmetap(i4)=max(ps(5),ps(7))-max(ps(1),ps(3))
|
|
bmetap(i2)=max(ps(3),ps(7))-max(ps(1),ps(5))
|
|
endif
|
|
|
|
! bit 154 lives in symbol 52 and will be 0 if it is set as an ap bit
|
|
! take care of metrics for bits 155 and 156
|
|
if(j.eq.52) then ! bit 154 will be 0 if it is set as an ap bit.
|
|
bmetap(i2)=max(ps(2),ps(3))-max(ps(0),ps(1))
|
|
bmetap(i1)=max(ps(1),ps(3))-max(ps(0),ps(2))
|
|
endif
|
|
|
|
enddo
|
|
|
|
call normalizebmet(bmeta,3*ND)
|
|
call normalizebmet(bmetb,3*ND)
|
|
call normalizebmet(bmetap,3*ND)
|
|
|
|
scalefac=2.83
|
|
llr0=scalefac*bmeta
|
|
llr1=scalefac*bmetb
|
|
llra=scalefac*bmetap ! llr's for use with ap
|
|
apmag=scalefac*(maxval(abs(bmetap))*1.01)
|
|
|
|
! pass #
|
|
!------------------------------
|
|
! 1 regular decoding
|
|
! 2 erase 24
|
|
! 3 erase 48
|
|
! 4 ap pass 1
|
|
! 5 ap pass 2
|
|
! 6 ap pass 3
|
|
! 7 ap pass 4, etc.
|
|
|
|
if(lapon) then
|
|
if(.not.lapcqonly) then
|
|
npasses=4+nappasses(nQSOProgress)
|
|
else
|
|
npasses=5
|
|
endif
|
|
else
|
|
npasses=4
|
|
endif
|
|
|
|
do ipass=1,npasses
|
|
|
|
llr=llr0
|
|
if(ipass.eq.2) llr=llr1
|
|
if(ipass.eq.3) llr(1:24)=0.
|
|
if(ipass.eq.4) llr(1:48)=0.
|
|
if(ipass.le.4) then
|
|
apmask=0
|
|
llrap=llr
|
|
iaptype=0
|
|
endif
|
|
|
|
if(ipass .gt. 4) then
|
|
if(.not.lapcqonly) then
|
|
iaptype=naptypes(nQSOProgress,ipass-4)
|
|
else
|
|
iaptype=1
|
|
endif
|
|
if(iaptype.ge.3 .and. (abs(f1-nfqso).gt.napwid .and. abs(f1-nftx).gt.napwid) ) cycle
|
|
if(iaptype.eq.1 .or. iaptype.eq.2 ) then ! AP,???,???
|
|
apmask=0
|
|
apmask(88:115)=1 ! first 28 bits are AP
|
|
apmask(144)=1 ! not free text
|
|
llrap=llr
|
|
if(iaptype.eq.1) llrap(88:115)=apmag*mcq
|
|
if(iaptype.eq.2) llrap(88:115)=apmag*apsym(1:28)
|
|
llrap(116:117)=llra(116:117)
|
|
llrap(142:143)=llra(142:143)
|
|
llrap(144)=-apmag
|
|
endif
|
|
if(iaptype.eq.3) then ! mycall, dxcall, ???
|
|
apmask=0
|
|
apmask(88:115)=1 ! mycall
|
|
apmask(116:143)=1 ! hiscall
|
|
apmask(144)=1 ! not free text
|
|
llrap=llr
|
|
llrap(88:143)=apmag*apsym(1:56)
|
|
llrap(144)=-apmag
|
|
endif
|
|
if(iaptype.eq.4 .or. iaptype.eq.5 .or. iaptype.eq.6) then
|
|
apmask=0
|
|
apmask(88:115)=1 ! mycall
|
|
apmask(116:143)=1 ! hiscall
|
|
apmask(144:159)=1 ! RRR or 73 or RR73
|
|
llrap=llr
|
|
llrap(88:143)=apmag*apsym(1:56)
|
|
if(iaptype.eq.4) llrap(144:159)=apmag*mrrr
|
|
if(iaptype.eq.5) llrap(144:159)=apmag*m73
|
|
if(iaptype.eq.6) llrap(144:159)=apmag*mrr73
|
|
endif
|
|
if(iaptype.eq.7) then ! ???, dxcall, ???
|
|
apmask=0
|
|
apmask(116:143)=1 ! hiscall
|
|
apmask(144)=1 ! not free text
|
|
llrap=llr
|
|
llrap(115)=llra(115)
|
|
llrap(116:143)=apmag*apsym(29:56)
|
|
llrap(144)=-apmag
|
|
endif
|
|
endif
|
|
|
|
cw=0
|
|
call timer('bpd174 ',0)
|
|
call bpdecode174(llrap,apmask,max_iterations,decoded,cw,nharderrors, &
|
|
niterations)
|
|
call timer('bpd174 ',1)
|
|
dmin=0.0
|
|
if(ndepth.eq.3 .and. nharderrors.lt.0) then
|
|
ndeep=3
|
|
if(abs(nfqso-f1).le.napwid .or. abs(nftx-f1).le.napwid) then
|
|
if((ipass.eq.3 .or. ipass.eq.4) .and. .not.nagain) then
|
|
ndeep=3
|
|
else
|
|
ndeep=4
|
|
endif
|
|
endif
|
|
if(nagain) ndeep=5
|
|
call timer('osd174 ',0)
|
|
call osd174(llrap,apmask,ndeep,decoded,cw,nharderrors,dmin)
|
|
call timer('osd174 ',1)
|
|
endif
|
|
nbadcrc=1
|
|
message=' '
|
|
xsnr=-99.0
|
|
if(count(cw.eq.0).eq.174) cycle !Reject the all-zero codeword
|
|
if(nharderrors.ge.0 .and. nharderrors+dmin.lt.60.0 .and. &
|
|
.not.(sync.lt.2.0 .and. nharderrors.gt.35) .and. &
|
|
.not.(ipass.gt.2 .and. nharderrors.gt.39) .and. &
|
|
.not.(ipass.eq.4 .and. nharderrors.gt.30) &
|
|
) then
|
|
call chkcrc12a(decoded,nbadcrc)
|
|
else
|
|
nharderrors=-1
|
|
cycle
|
|
endif
|
|
i3bit=4*decoded(73) + 2*decoded(74) + decoded(75)
|
|
if(nbadcrc.eq.0) then
|
|
decoded0=decoded
|
|
call extractmessage174(decoded,origmsg,ncrcflag)
|
|
decoded=decoded0
|
|
|
|
message(1:12)=origmsg(1:12)
|
|
call genft8(message,mygrid6,bcontest,i3bit,msgsent,msgbits,itone)
|
|
if(lsubtract) call subtractft8(dd0,itone,f1,xdt2)
|
|
xsig=0.0
|
|
xnoi=0.0
|
|
do i=1,NN
|
|
xsig=xsig+s2(itone(i),i)**2
|
|
ios=mod(itone(i)+4,7)
|
|
xnoi=xnoi+s2(ios,i)**2
|
|
enddo
|
|
xsnr=0.001
|
|
if(xnoi.gt.0 .and. xnoi.lt.xsig) xsnr=xsig/xnoi-1.0
|
|
xsnr=10.0*log10(xsnr)-27.0
|
|
xsnr2=db(xsig/xbase - 1.0) - 32.0
|
|
if(.not.nagain) xsnr=xsnr2
|
|
if(xsnr .lt. -24.0) xsnr=-24.0
|
|
|
|
msg37=origmsg//' '
|
|
|
|
msg37(22:22) = char(48 + i3bit)
|
|
|
|
return
|
|
endif
|
|
enddo
|
|
|
|
return
|
|
end subroutine ft8b
|
|
|
|
subroutine normalizebmet(bmet,n)
|
|
real bmet(n)
|
|
|
|
bmetav=sum(bmet)/real(n)
|
|
bmet2av=sum(bmet*bmet)/real(n)
|
|
var=bmet2av-bmetav*bmetav
|
|
if( var .gt. 0.0 ) then
|
|
bmetsig=sqrt(var)
|
|
else
|
|
bmetsig=sqrt(bmet2av)
|
|
endif
|
|
bmet=bmet/bmetsig
|
|
return
|
|
end subroutine normalizebmet
|
|
|
|
|
|
function bessi0(x)
|
|
! From Numerical Recipes
|
|
real bessi0,x
|
|
double precision p1,p2,p3,p4,p5,p6,p7,q1,q2,q3,q4,q5,q6,q7,q8,q9,y
|
|
save p1,p2,p3,p4,p5,p6,p7,q1,q2,q3,q4,q5,q6,q7,q8,q9
|
|
data p1,p2,p3,p4,p5,p6,p7/1.0d0,3.5156229d0,3.0899424d0,1.2067492d0, &
|
|
0.2659732d0,0.360768d-1,0.45813d-2/
|
|
data q1,q2,q3,q4,q5,q6,q7,q8,q9/0.39894228d0,0.1328592d-1, &
|
|
0.225319d-2,-0.157565d-2,0.916281d-2,-0.2057706d-1, &
|
|
0.2635537d-1,-0.1647633d-1,0.392377d-2/
|
|
|
|
if (abs(x).lt.3.75) then
|
|
y=(x/3.75)**2
|
|
bessi0=p1+y*(p2+y*(p3+y*(p4+y*(p5+y*(p6+y*p7)))))
|
|
else
|
|
ax=abs(x)
|
|
y=3.75/ax
|
|
bessi0=(exp(ax)/sqrt(ax))*(q1+y*(q2+y*(q3+y*(q4 &
|
|
+y*(q5+y*(q6+y*(q7+y*(q8+y*q9))))))))
|
|
endif
|
|
return
|
|
end function bessi0
|
|
|