+// ----------------------------------------------------------------------------
+// $Id$
+// ----------------------------------------------------------------------------
+// Public Domain C Library - http://pdclib.sourceforge.net
+// This code is Public Domain. Use, modify, and redistribute at will.
+// ----------------------------------------------------------------------------
+
+// ----------------------------------------------------------------------------
+// C++
+
+float acosh( float x ) { /* TODO */ };
+long double acosh( long double x ) { /* TODO */ };
+
+// ----------------------------------------------------------------------------
+// Standard C
+
+double acosh( double x ) { /* TODO */ };
+float acoshf( float x ) { /* TODO */ };
+long double acoshl( long double x ) { /* TODO */ };