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fvn_fnlib/alnrel.f
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function alnrel (x)
c april 1977 version. w. fullerton, c3, los alamos scientific lab.
dimension alnrcs(23)
external csevl, inits, r1mach
c
c series for alnr on the interval -3.75000d-01 to 3.75000d-01
c with weighted error 1.93e-17
c log weighted error 16.72
c significant figures required 16.44
c decimal places required 17.40
c
data alnrcs( 1) / 1.0378693562 743770e0 /
data alnrcs( 2) / -.1336430150 4908918e0 /
data alnrcs( 3) / .0194082491 35520563e0 /
data alnrcs( 4) / -.0030107551 12753577e0 /
data alnrcs( 5) / .0004869461 47971548e0 /
data alnrcs( 6) / -.0000810548 81893175e0 /
data alnrcs( 7) / .0000137788 47799559e0 /
data alnrcs( 8) / -.0000023802 21089435e0 /
data alnrcs( 9) / .0000004164 04162138e0 /
data alnrcs(10) / -.0000000735 95828378e0 /
data alnrcs(11) / .0000000131 17611876e0 /
data alnrcs(12) / -.0000000023 54670931e0 /
data alnrcs(13) / .0000000004 25227732e0 /
data alnrcs(14) / -.0000000000 77190894e0 /
data alnrcs(15) / .0000000000 14075746e0 /
data alnrcs(16) / -.0000000000 02576907e0 /
data alnrcs(17) / .0000000000 00473424e0 /
data alnrcs(18) / -.0000000000 00087249e0 /
data alnrcs(19) / .0000000000 00016124e0 /
data alnrcs(20) / -.0000000000 00002987e0 /
data alnrcs(21) / .0000000000 00000554e0 /
data alnrcs(22) / -.0000000000 00000103e0 /
data alnrcs(23) / .0000000000 00000019e0 /
c
data nlnrel, xmin /0, 0./
c
if (nlnrel.ne.0) go to 10
nlnrel = inits (alnrcs, 23, 0.1*r1mach(3))
xmin = -1.0 + sqrt(r1mach(4))
c
10 if (x.le.(-1.0)) call seteru (
1 18halnrel x is le -1, 18, 2, 2)
if (x.lt.xmin) call seteru (
1 54halnrel answer lt half precision because x too near -1, 54,
2 1, 1)
c
if (abs(x).le.0.375) alnrel = x*(1. -
1 x*csevl (x/.375, alnrcs, nlnrel))
if (abs(x).gt.0.375) alnrel = alog (1.0+x)
c
return
end
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