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authorEli Zaretskii <eliz@gnu.org>2002-02-19 11:03:54 +0000
committerEli Zaretskii <eliz@gnu.org>2002-02-19 11:03:54 +0000
commit4b4477b4d757371609d59cd447005c7012095730 (patch)
treef200a33a144237f05c57c436cc9a4f03f6a19567 /lispref/numbers.texi
parenta1e3675807f4528487a2a877a0445110ecfeb35b (diff)
downloademacs-4b4477b4d757371609d59cd447005c7012095730.tar.gz
(Math Functions): Document the optional second arg of atan.
Diffstat (limited to 'lispref/numbers.texi')
-rw-r--r--lispref/numbers.texi9
1 files changed, 6 insertions, 3 deletions
diff --git a/lispref/numbers.texi b/lispref/numbers.texi
index 9689d5cedfe..e13bd04117a 100644
--- a/lispref/numbers.texi
+++ b/lispref/numbers.texi
@@ -1046,8 +1046,8 @@ pi
is out of range (outside [-1, 1]), then the result is a NaN.
@end defun
-@defun atan arg
-The value of @code{(atan @var{arg})} is a number between
+@defun atan y &optional x
+The value of @code{(atan @var{y})} is a number between
@ifnottex
@minus{}pi/2
@end ifnottex
@@ -1061,7 +1061,10 @@ pi/2
@tex
@math{\pi/2}
@end tex
-(exclusive) whose tangent is @var{arg}.
+(exclusive) whose tangent is @var{y}. If the optional second
+argument @var{x} is given, the value of @code{(atan y x)} is the
+angle in radians between the vector @code{[@var{x}, @var{y}]} and the
+@code{X} axis.
@end defun
@defun exp arg