function besi0 (x) c april 1977 version. w. fullerton, c3, los alamos scientific lab. dimension bi0cs(12) external besi0e, csevl, inits, r1mach c c series for bi0 on the interval 0. to 9.00000d+00 c with weighted error 2.46e-18 c log weighted error 17.61 c significant figures required 17.90 c decimal places required 18.15 c data bi0 cs( 1) / -.0766054725 2839144951e0 / data bi0 cs( 2) / 1.9273379539 93808270e0 / data bi0 cs( 3) / .2282644586 920301339e0 / data bi0 cs( 4) / .0130489146 6707290428e0 / data bi0 cs( 5) / .0004344270 9008164874e0 / data bi0 cs( 6) / .0000094226 5768600193e0 / data bi0 cs( 7) / .0000001434 0062895106e0 / data bi0 cs( 8) / .0000000016 1384906966e0 / data bi0 cs( 9) / .0000000000 1396650044e0 / data bi0 cs(10) / .0000000000 0009579451e0 / data bi0 cs(11) / .0000000000 0000053339e0 / data bi0 cs(12) / .0000000000 0000000245e0 / c data nti0, xsml, xmax / 0, 0., 0. / c if (nti0.ne.0) go to 10 nti0 = inits (bi0cs, 12, 0.1*r1mach(3)) xsml = sqrt (4.0*r1mach(3)) xmax = alog (r1mach(2)) c 10 y = abs(x) if (y.gt.3.0) go to 20 c besi0 = 1.0 if (y.gt.xsml) besi0 = 2.75 + csevl (y*y/4.5-1.0, bi0cs, nti0) return c 20 if (y.gt.xmax) call seteru (34hbesi0 abs(x) so big i0 overflows, 1 34, 1, 2) c besi0 = exp(y) * besi0e(x) c return end