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

Michael Niedermayer michaelni at gmx.at
Thu Jan 24 00:17:38 CET 2013

On Wed, Jan 23, 2013 at 07:18:48PM +0100, Stefano Sabatini wrote:
> ---
>  doc/eval.texi |    8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> diff --git a/doc/eval.texi b/doc/eval.texi
> index 3fd6ca9..f06f7ad 100644
> --- a/doc/eval.texi
> +++ b/doc/eval.texi
> @@ -170,8 +170,12 @@ Note, when you have the derivatives at y instead of 0,
>  converge the result is undefined.
>  @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 x where the function with argument @code{ld(0)} in @var{expr} is
> +0 in the interval 0.. at var{max}.
> +
> +The value in @code{ld(0)} is modified during the computation. The
> +expression must denote a continuous function or the result is
> +undefined.
>  @end table

I wrote the code
I dont understand the docs you write

if you want to make it clearer IMHO put less in the sentance and
clearer not more

Finds the value x at which f(x)=0 in the interval 0 <= x <= max.
ld(0) is used to represent x, that means that your given expression
will be evaluated multiple times with various values of x that the
expression can access through ld(0).
When your expression evaluates to 0 then the value of ld(0) will be
returned by root()

f() must be continuous or the result is undefined.

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Freedom in capitalist society always remains about the same as it was in
ancient Greek republics: Freedom for slave owners. -- Vladimir Lenin
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