Merge pull request #19 from certik/docs

polyroots: clarify a docstring about extraprec
2014-04-13 13:43:49 +02:00
parent 0f02c47336 5fb8631b3a
commit 9207fb2f7f
1 changed files with 4 additions and 0 deletions
@@ -108,6 +108,10 @@ def polyroots(ctx, coeffs, maxsteps=50, cleanup=True, extraprec=10,
    `maxsteps` (in which case increasing `maxsteps` should fix the problem), or
    a combination of both.

+    The user should always do a convergence study with regards to `extraprec`
+    to ensure accurate results. It is possible to get convergence to a wrong
+    answer with too low `extraprec`.
+
    Provided there are no repeated roots, :func:`~mpmath.polyroots` can
    typically compute all roots of an arbitrary polynomial to high precision::