@section gcd: greatest common divisor
@findex gcd
+@c Copyright (C) 2006 Free Software Foundation, Inc.
+
+@c Permission is granted to copy, distribute and/or modify this document
+@c under the terms of the GNU Free Documentation License, Version 1.3 or
+@c any later version published by the Free Software Foundation; with no
+@c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+@c Texts. A copy of the license is included in the ``GNU Free
+@c Documentation License'' file as part of this distribution.
+
The @code{gcd} function returns the greatest common divisor of two numbers
@code{a > 0} and @code{b > 0}. It is the caller's responsibility to ensure
that the arguments are non-zero.