double precision function dbesy0 (x) c august 1980 edition. w. fullerton, c3, los alamos scientific lab. double precision x, by0cs(19), ampl, theta, twodpi, xsml, 1 y, alnhaf, d1mach, dcsevl, dbesj0, dlog, dsin, dsqrt external d1mach, dbesj0, dcsevl, initds c c series for by0 on the interval 0. to 1.60000e+01 c with weighted error 8.14e-32 c log weighted error 31.09 c significant figures required 30.31 c decimal places required 31.73 c data by0 cs( 1) / -.1127783939 2865573217 9398054602 8 d-1 / data by0 cs( 2) / -.1283452375 6042034604 8088453183 8 d+0 / data by0 cs( 3) / -.1043788479 9794249365 8176227661 8 d+0 / data by0 cs( 4) / +.2366274918 3969695409 2415926461 3 d-1 / data by0 cs( 5) / -.2090391647 7004862391 9622395034 2 d-2 / data by0 cs( 6) / +.1039754539 3905725209 9924657638 1 d-3 / data by0 cs( 7) / -.3369747162 4239720967 1877534503 7 d-5 / data by0 cs( 8) / +.7729384267 6706671585 2136721637 1 d-7 / data by0 cs( 9) / -.1324976772 6642595914 4347606896 4 d-8 / data by0 cs( 10) / +.1764823261 5404527921 0038936315 8 d-10 / data by0 cs( 11) / -.1881055071 5801962006 0282301206 9 d-12 / data by0 cs( 12) / +.1641865485 3661495027 9223718574 9 d-14 / data by0 cs( 13) / -.1195659438 6046060857 4599100672 0 d-16 / data by0 cs( 14) / +.7377296297 4401858424 9411242666 6 d-19 / data by0 cs( 15) / -.3906843476 7104373307 4090666666 6 d-21 / data by0 cs( 16) / +.1795503664 4361579498 2912000000 0 d-23 / data by0 cs( 17) / -.7229627125 4480104789 3333333333 3 d-26 / data by0 cs( 18) / +.2571727931 6351685973 3333333333 3 d-28 / data by0 cs( 19) / -.8141268814 1636949333 3333333333 3 d-31 / c data twodpi / 0.6366197723 6758134307 5535053490 057 d0 / data alnhaf /-0.6931471805 5994530941 7232121458 18d0 / data nty0, xsml / 0, 0.d0 / c if (nty0.ne.0) go to 10 nty0 = initds (by0cs, 19, 0.1*sngl(d1mach(3))) xsml = dsqrt (4.0d0*d1mach(3)) c 10 if (x.le.0.d0) call seteru (29hdbesy0 x is zero or negative, 29, 1 1, 2) if (x.gt.4.0d0) go to 20 c y = 0.d0 if (x.gt.xsml) y = x*x dbesy0 = twodpi*(alnhaf+dlog(x))*dbesj0(x) + .375d0 1 + dcsevl (.125d0*y-1.d0, by0cs, nty0) return c 20 call d9b0mp (x, ampl, theta) dbesy0 = ampl * dsin(theta) return c end