function aide (x)
c july 1980 edition.  w. fullerton, bell labs.
c
c evaluate the derivative of the airy function for x .le. 0
c and evaluate aid(x)*exp(zeta) for x .ge. 0 where
c    zeta = 2/3 * x**(3/2)
c
      dimension aifcs(8), aigcs(9), aip1cs(25), aip2cs(15)
      external cos, csevl, exp, inits, r1mach, sqrt
c
c series for aif on the interval -1.00000e+00 to  1.00000e+00
c                                        with weighted error   5.22e-18
c                                         log weighted error  17.28
c                               significant figures required  16.01
c                                    decimal places required  17.73
c
      data aifcs(  1) /     0.1052746122 6531408809 e0/
      data aifcs(  2) /     0.0118361362 8152997844 e0/
      data aifcs(  3) /     0.0001232810 4173225664 e0/
      data aifcs(  4) /     0.0000006226 1225638140 e0/
      data aifcs(  5) /     0.0000000018 5298887844 e0/
      data aifcs(  6) /     0.0000000000 0363328873 e0/
      data aifcs(  7) /     0.0000000000 0000504622 e0/
      data aifcs(  8) /     0.0000000000 0000000522 e0/
c
c series for aig on the interval -1.00000e+00 to  1.00000e+00
c                                        with weighted error   3.14e-19
c                                         log weighted error  18.50
c                               significant figures required  17.44
c                                    decimal places required  18.98
c
      data aigcs(  1) /     0.0212338781 5091866685 2e0/
      data aigcs(  2) /     0.0863159303 3521440675 2e0/
      data aigcs(  3) /     0.0017975947 2038323135 8e0/
      data aigcs(  4) /     0.0000142654 9987555069 3e0/
      data aigcs(  5) /     0.0000000594 3799528368 3e0/
      data aigcs(  6) /     0.0000000001 5240336647 9e0/
      data aigcs(  7) /     0.0000000000 0026458766 0e0/
      data aigcs(  8) /     0.0000000000 0000033156 2e0/
      data aigcs(  9) /     0.0000000000 0000000031 4e0/
c
c series for aip2 on the interval  0.00000e+00 to  1.25000e-01
c                                        with weighted error   2.15e-17
c                                         log weighted error  16.67
c                               significant figures required  14.27
c                                    decimal places required  17.26
c
      data aip2cs(  1) /     0.0065457691 989713757 e0/
      data aip2cs(  2) /     0.0023833724 120774592 e0/
      data aip2cs(  3) /    -0.0000430700 770220586 e0/
      data aip2cs(  4) /     0.0000015629 125858629 e0/
      data aip2cs(  5) /    -0.0000000815 417186163 e0/
      data aip2cs(  6) /     0.0000000054 103738057 e0/
      data aip2cs(  7) /    -0.0000000004 284130883 e0/
      data aip2cs(  8) /     0.0000000000 389497963 e0/
      data aip2cs(  9) /    -0.0000000000 039623161 e0/
      data aip2cs( 10) /     0.0000000000 004428184 e0/
      data aip2cs( 11) /    -0.0000000000 000536297 e0/
      data aip2cs( 12) /     0.0000000000 000069650 e0/
      data aip2cs( 13) /    -0.0000000000 000009620 e0/
      data aip2cs( 14) /     0.0000000000 000001403 e0/
      data aip2cs( 15) /    -0.0000000000 000000215 e0/
c
c series for aip1 on the interval  1.25000e-01 to  1.00000e+00
c                                        with weighted error   2.60e-17
c                                         log weighted error  16.58
c                               significant figures required  14.91
c                                    decimal places required  17.28
c
      data aip1cs(  1) /     0.0358865097 808301538 e0/
      data aip1cs(  2) /     0.0114668575 627764899 e0/
      data aip1cs(  3) /    -0.0007592073 583861400 e0/
      data aip1cs(  4) /     0.0000869517 610893841 e0/
      data aip1cs(  5) /    -0.0000128237 294298592 e0/
      data aip1cs(  6) /     0.0000022062 695681038 e0/
      data aip1cs(  7) /    -0.0000004222 295185921 e0/
      data aip1cs(  8) /     0.0000000874 686415726 e0/
      data aip1cs(  9) /    -0.0000000192 773588418 e0/
      data aip1cs( 10) /     0.0000000044 668460054 e0/
      data aip1cs( 11) /    -0.0000000010 790108052 e0/
      data aip1cs( 12) /     0.0000000002 700029447 e0/
      data aip1cs( 13) /    -0.0000000000 696480108 e0/
      data aip1cs( 14) /     0.0000000000 184489907 e0/
      data aip1cs( 15) /    -0.0000000000 050027817 e0/
      data aip1cs( 16) /     0.0000000000 013852243 e0/
      data aip1cs( 17) /    -0.0000000000 003908218 e0/
      data aip1cs( 18) /     0.0000000000 001121536 e0/
      data aip1cs( 19) /    -0.0000000000 000326862 e0/
      data aip1cs( 20) /     0.0000000000 000096619 e0/
      data aip1cs( 21) /    -0.0000000000 000028935 e0/
      data aip1cs( 22) /     0.0000000000 000008770 e0/
      data aip1cs( 23) /    -0.0000000000 000002688 e0/
      data aip1cs( 24) /     0.0000000000 000000832 e0/
      data aip1cs( 25) /    -0.0000000000 000000260 e0/
c
      data naif, naig, naip1, naip2 / 4*0 /
      data x2sml, x3sml, x32sml, xbig / 4*0.0 /
c
      if (naif.ne.0) go to 10
      eta = 0.1*r1mach(3)
      naif = inits (aifcs, 8, eta)
      naig = inits (aigcs, 9, eta)
      naip1 = inits (aip1cs, 25, eta)
      naip2 = inits (aip2cs, 15, eta)
c
      x2sml = sqrt (eta)
      x3sml = eta**0.3333
      x32sml = 1.3104*x3sml**2
      xbig = r1mach(2)**0.6666
c
 10   if (x.ge.(-1.0)) go to 20
      call r9admp (x, xn, phi)
      aide = xn * cos(phi)
      return
c
 20   if (x.gt.1.0) go to 30
      x3 = 0.0
      if (abs(x).gt.x3sml) x3 = x**3
      x2 = 0.0
      if (abs(x).gt.x2sml) x2 = x*x
      aide = (x2*(0.125 + csevl (x3, aifcs, naif)) -
     1  csevl (x3, aigcs, naig)) - 0.25
      if (x.gt.x32sml) aide = aide * exp (2.0*x*sqrt(x)/3.0)
      return
c
 30   if (x.gt.4.0) go to 40
      sqrtx = sqrt(x)
      z = (16.0/(x*sqrtx) - 9.0)/7.0
      aide = (-0.28125 - csevl (z, aip1cs, naip1)) * sqrt(sqrtx)
      return
c
 40   sqrtx = sqrt(x)
      z = -1.0
      if (x.lt.xbig) z = 16.0/(x*sqrtx) - 1.0
      aide = (-0.28125 - csevl (z, aip2cs, naip2)) * sqrt(sqrtx)
      return
c
      end