@comment math.h
@comment ANSI
@deftypefun double tanh (double @var{x})
-This function returns the hyperbolic tangent of @var{x}, defined
-mathematically as @w{@code{sinh (@var{x}) / cosh (@var{x})}}.
+This function returns the hyperbolic tangent of @var{x}, whose
+mathematical definition is @w{@code{sinh (@var{x}) / cosh (@var{x})}}.
@end deftypefun
@cindex inverse hyperbolic functions