Better terminology for ‘long double’ in manual

* manual/math.texi (Mathematical Constants):
Don’t say that long double is “the same as” double, as the
types remain distinct (problem reported by Keith Thompson).
Also, don’t imply that float is the “narrowest”, as floating
point types don’t have widths in Standard C.  Instead, talk
about precision and exponent range.

diff --git a/manual/math.texi b/manual/math.texi
index fbabf37b4812fb97affd1a4e638aa90dda756839..fd7284953d3599021e31da8ea8293ff2553f0a78 100644 (file)
--- a/manual/math.texi
+++ b/manual/math.texi
@@ -48,10 +48,10 @@ versions are from the numeric extensions to C included in @w{ISO C99}.
 Which of the three versions of a function should be used depends on the
 situation.  For most calculations, the @code{float} functions are the
 fastest.  On the other hand, the @code{long double} functions have the
-highest precision.  @code{double} is somewhere in between.  It is
-usually wise to pick the narrowest type that can accommodate your data.
-Not all machines have a distinct @code{long double} type; it may be the
-same as @code{double}.
+most precision and exponent range.  @code{double} is somewhere in between.
+It is usually wise to pick the smallest type that can accommodate your data.
+On some machines @code{long double} has no more precision or exponent
+range than @code{double}, though the types remain distinct for type checking.
 
 @Theglibc{} also provides @code{_Float@var{N}} and
 @code{_Float@var{N}x} types.  These types are defined in @w{ISO/IEC TS