1 files changed, 4 insertions, 0 deletions
diff --git a/src/zeta.c b/src/zeta.c
index e76716ce8..164a4fdf8 100644
--- a/src/zeta.c
+++ b/src/zeta.c
@@ -414,6 +414,10 @@ mpfr_zeta (mpfr_t z, mpfr_srcptr s, mpfr_rnd_t rnd_mode)
       /* add = 1 + floor(log(c*c*c*(13 + m1))/log(2)); */
       add = __gmpfr_ceil_log2 (c * c * c * (13.0 + m1));
       prec1 = precz + add;
+      /* FIXME: to avoid that the working precision (prec1) depends on the
+         input precision, one would need to take into account the error made
+         when s1 is not exactly 1-s when computing zeta(s1) and gamma(s1)
+         below, and also in the case y=Inf (i.e. when gamma(s1) overflows). */
       prec1 = MAX (prec1, precs1) + 10;
 
       MPFR_GROUP_INIT_4 (group, prec1, z_pre, s1, y, p);