function inits (os, nos, eta)
c april 1977 version.  w. fullerton, c3, los alamos scientific lab.
c
c initialize the orthogonal series so that inits is the number of terms
c needed to insure the error is no larger than eta.  ordinarily, eta
c will be chosen to be one-tenth machine precision.
c
c             input arguments --
c os     array of nos coefficients in an orthogonal series.
c nos    number of coefficients in os.
c eta    requested accuracy of series.
c
      dimension os(nos)
c
      if (nos.lt.1) call seteru (
     1  35hinits   number of coefficients lt 1, 35, 2, 2)
c
      err = 0.
      do 10 ii=1,nos
        i = nos + 1 - ii
        err = err + abs(os(i))
        if (err.gt.eta) go to 20
 10   continue
c
 20   if (i.eq.nos) call seteru (28hinits   eta may be too small, 28,
     1  1, 2)
      inits = i
c
      return
      end