[FFmpeg-cvslog] doc/eval: fix/extend documentation for root() function

[Stefano Sabatini]

ffmpeg | branch: master | Stefano Sabatini <stefasab at gmail.com> | Wed Jan 23 11:45:31 2013 +0100| [d99bc8475232ef7f72042c7a7328b77cc3771fa4] | committer: Stefano Sabatini

doc/eval: fix/extend documentation for root() function

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d99bc8475232ef7f72042c7a7328b77cc3771fa4
---

 doc/eval.texi |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/doc/eval.texi b/doc/eval.texi
index f77b87d..37ca137 100644
--- a/doc/eval.texi
+++ b/doc/eval.texi
@@ -175,8 +175,17 @@ When the series does not converge the results are undefined.
 Return the current (wallclock) time in seconds.
 
 @item root(expr, max)
-Finds x where f(x)=0 in the interval 0..max.
-f() must be continuous or the result is undefined.
+Find an input value for which the function represented by @var{expr}
+with argument @var{ld(0)} is 0 in the interval 0.. at var{max}.
+
+The expression in @var{expr} must denote a continuous function or the
+result is undefined.
+
+ at var{ld(0)} is used to represent the function input value, which means
+that the given expression will be evaluated multiple times with
+various input values that the expression can access through
+ at code{ld(0)}. When the expression evaluates to 0 then the
+corresponding input value will be returned.
 @end table
 
 The following constants are available: