function r9lgmc (x)
  c august 1977 edition.  w. fullerton, c3, los alamos scientific lab.
  c
  c compute the log gamma correction factor for x .ge. 10.0 so that
  c  alog (gamma(x)) = alog(sqrt(2*pi)) + (x-.5)*alog(x) - x + r9lgmc(x)
  c
        dimension algmcs(6)
        external csevl,inits, r1mach
  c
  c series for algm       on the interval  0.          to  1.00000d-02
  c                                        with weighted error   3.40e-16
  c                                         log weighted error  15.47
  c                               significant figures required  14.39
  c                                    decimal places required  15.86
  c
        data algmcs( 1) /    .1666389480 45186e0 /
        data algmcs( 2) /   -.0000138494 817606e0 /
        data algmcs( 3) /    .0000000098 108256e0 /
        data algmcs( 4) /   -.0000000000 180912e0 /
        data algmcs( 5) /    .0000000000 000622e0 /
        data algmcs( 6) /   -.0000000000 000003e0 /
  c
        data nalgm, xbig, xmax / 0, 2*0.0 /
  c
        if (nalgm.ne.0) go to 10
        nalgm = inits (algmcs, 6, r1mach(3))
        xbig = 1.0/sqrt(r1mach(3))
        xmax = exp (amin1(alog(r1mach(2)/12.0), -alog(12.0*r1mach(1))) )
  c
   10   if (x.lt.10.0) call seteru (23hr9lgmc  x must be ge 10, 23, 1, 2)
        if (x.ge.xmax) go to 20
  c
        r9lgmc = 1.0/(12.0*x)
        if (x.lt.xbig) r9lgmc = csevl (2.0*(10./x)**2-1., algmcs, nalgm)/x
        return
  c
   20   r9lgmc = 0.0
        call seteru (34hr9lgmc  x so big r9lgmc underflows, 34, 2, 0)
        return
  c
        end