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diff --git a/doc/eval.texi b/doc/eval.texi index 7d8106b..18d8487 100644 --- a/doc/eval.texi +++ b/doc/eval.texi @@ -1,7 +1,7 @@ @chapter Expression Evaluation @c man begin EXPRESSION EVALUATION -When evaluating an arithemetic expression, Libav uses an internal +When evaluating an arithemetic expression, FFmpeg uses an internal formula evaluator, implemented through the @file{libavutil/eval.h} interface. @@ -79,6 +79,34 @@ Compute the square root of @var{expr}. This is equivalent to @item not(expr) Return 1.0 if @var{expr} is zero, 0.0 otherwise. + +@item pow(x, y) +Compute the power of @var{x} elevated @var{y}, it is equivalent to +"(@var{x})^(@var{y})". + +@item random(x) +Return a pseudo random value between 0.0 and 1.0. @var{x} is the index of the +internal variable which will be used to save the seed/state. + +@item hypot(x, y) +This function is similar to the C function with the same name; it returns +"sqrt(@var{x}*@var{x} + @var{y}*@var{y})", the length of the hypotenuse of a +right triangle with sides of length @var{x} and @var{y}, or the distance of the +point (@var{x}, @var{y}) from the origin. + +@item gcd(x, y) +Return the greatest common divisor of @var{x} and @var{y}. If both @var{x} and +@var{y} are 0 or either or both are less than zero then behavior is undefined. +@end table + +The following constants are available: +@table @option +@item PI +area of the unit disc, approximatively 3.14 +@item E +exp(1) (Euler's number), approximatively 2.718 +@item PHI +golden ratio (1+sqrt(5))/2, approximatively 1.618 @end table Note that: |
