Computes any branch \(W_{k}\) of the multiple-valued Lambert \(W\) function. \(W(z)\) is the set of solutions \(w\) of the equation \(w e^{w} = z\).
arb_lambertw(x,         flags = 0L, prec = flintPrec())
acb_lambertw(z, k = 0L, flags = 0L, prec = flintPrec())An arb or acb vector
  storing function values with error bounds.  Its length is the maximum
  of the lengths of the arguments or zero (zero if any argument has
  length zero).  The arguments are recycled as necessary.
numeric, complex, arb, or
    acb vectors.
an integer or fmpz vector listing indices
    of branches of the function.  0 indicates the principal
    branch.
for arb_lambertw:
    an integer vector indicating which of the index 0 and index -1
    branches is computed (0 means index 0, 1 means index
    -1).
    
    for acb_lambertw:
    an integer vector indicating how branch cuts are defined.
    Nonzero values are nonstandard; see the first reference.
a numeric or slong vector indicating the
    desired precision as a number of bits.
The FLINT documentation of the underlying C functions: https://flintlib.org/doc/arb.html, https://flintlib.org/doc/acb.html
NIST Digital Library of Mathematical Functions: https://dlmf.nist.gov/4.13
Classes arb and acb.