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double precision function dci (x)
c december 1980 edition, w. fullerton, bell labs.
double precision x, cics(19), xsml, y, f, g, sinx, dcsevl,
1 d1mach, dcos, dlog, dsin, dsqrt
external d1mach, dcsevl, initds
c
c series for ci on the interval 0.00000e+00 to 1.60000e+01
c with weighted error 9.26e-33
c log weighted error 32.03
c significant figures required 32.06
c decimal places required 32.67
c
data ci cs( 1) / -0.3400428185 6055363156 2810766331 29873d0/
data ci cs( 2) / -1.0330216640 1177456807 1592710401 63751d0/
data ci cs( 3) / 0.1938822265 9917082876 7158746060 81709d0/
data ci cs( 4) / -0.0191826043 6019865893 9463462701 75301d0/
data ci cs( 5) / 0.0011078925 2584784967 1840980992 66118d0/
data ci cs( 6) / -0.0000415723 4558247208 8038402318 14601d0/
data ci cs( 7) / 0.0000010927 8524300228 7152955789 66285d0/
data ci cs( 8) / -0.0000000212 3285954183 4652196012 80329d0/
data ci cs( 9) / 0.0000000003 1733482164 3485448651 29873d0/
data ci cs( 10) / -0.0000000000 0376141547 9876836993 81798d0/
data ci cs( 11) / 0.0000000000 0003622653 4884839643 36956d0/
data ci cs( 12) / -0.0000000000 0000028911 5284936518 52433d0/
data ci cs( 13) / 0.0000000000 0000000194 3278606764 94420d0/
data ci cs( 14) / -0.0000000000 0000000001 1151831826 50184d0/
data ci cs( 15) / 0.0000000000 0000000000 0055278588 87706d0/
data ci cs( 16) / -0.0000000000 0000000000 0000239070 13943d0/
data ci cs( 17) / 0.0000000000 0000000000 0000000910 01612d0/
data ci cs( 18) / -0.0000000000 0000000000 0000000003 07233d0/
data ci cs( 19) / 0.0000000000 0000000000 0000000000 00926d0/
c
data nci, xsml /0, 0.0d0/
c
if (nci.ne.0) go to 10
nci = initds (cics, 19, 0.1*sngl(d1mach(3)))
xsml = dsqrt (d1mach(3))
c
10 if (x.le.0.0d0) call seteru (17hdci x is le 0, 17, 1, 2)
c
if (x.gt.4.0d0) go to 20
y = -1.0d0
if (x.gt.xsml) y = (x*x-8.d0)*0.125d0
c
dci = dlog(x) - 0.5d0 + dcsevl (y, cics, nci)
return
c
20 call d9sifg (x, f, g)
sinx = dsin (x)
call erroff
dci = f*sinx - g*dcos(x)
c
return
end
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