Merge remote-tracking branch 'qatar/master'

[ffmpeg] / doc / eval.texi

diff --git a/doc/eval.texi b/doc/eval.texi
index b41f31ec26ea113e249a12da738b693b91ce85cb..b325b37dff6599879c1502ee79685e0068595151 100644 (file)
--- 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, FFmpeg uses an internal
+When evaluating an arithmetic expression, FFmpeg uses an internal
 formula evaluator, implemented through the @file{libavutil/eval.h}
 interface.
 
@@ -50,10 +50,11 @@ Allow to store the value of the expression @var{expr} in an internal
 variable. @var{var} specifies the number of the variable where to
 store the value, and it is a value ranging from 0 to 9. The function
 returns the value stored in the internal variable.
+Note, Variables are currently not shared between expressions.
 
 @item ld(var)
 Allow to load the value of the internal variable with number
-@var{var}, which was previosly stored with st(@var{var}, @var{expr}).
+@var{var}, which was previously stored with st(@var{var}, @var{expr}).
 The function returns the loaded value.
 
 @item while(cond, expr)
@@ -99,6 +100,16 @@ 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, approximately 3.14
+@item E
+exp(1) (Euler's number), approximately 2.718
+@item PHI
+golden ratio (1+sqrt(5))/2, approximately 1.618
+@end table
+
 Note that:
 
 @code{*} works like AND