Added descriptions for log() and log10().

Clarified that floor() and ceil() return reals.  Same for the integer part
returned by modf().

Some markup consistency changes.

Doc/lib/libmath.tex

@@ -4,7 +4,7 @@
 \bimodindex{math}
 \renewcommand{\indexsubitem}{(in module math)}
 This module is always available.
-It provides access to the mathematical functions defined by the C
+It provides access to the mathematical functions defined by the \C{}
 standard.
 They are:
 
@@ -25,7 +25,7 @@ Return \code{atan(\var{x} / \var{y})}.
 \end{funcdesc}
 
 \begin{funcdesc}{ceil}{x}
-Return the ceiling of \var{x}.
+Return the ceiling of \var{x} as a real.
 \end{funcdesc}
 
 \begin{funcdesc}{cos}{x}
@@ -45,7 +45,7 @@ Return the absolute value of the real \var{x}.
 \end{funcdesc}
 
 \begin{funcdesc}{floor}{x}
-Return the floor of \var{x}.
+Return the floor of \var{x} as a real.
 \end{funcdesc}
 
 \begin{funcdesc}{fmod}{x, y}
@@ -65,9 +65,17 @@ Return the Euclidean distance, \code{sqrt(\var{x}*\var{x} + \var{y}*\var{y})}.
 Return \code{\var{x} * (2**\var{i})}.
 \end{funcdesc}
 
+\begin{funcdesc}{log}{x}
+Return the natural logarithm of \var{x}.
+\end{funcdesc}
+
+\begin{funcdesc}{log10}{x}
+Return the base-10 logarithm of \var{x}.
+\end{funcdesc}
+
 \begin{funcdesc}{modf}{x}
 Return the fractional and integer parts of \var{x}.  Both results
-carry the sign of \var{x}.
+carry the sign of \var{x}.  The integer part is returned as a real.
 \end{funcdesc}
 
 \begin{funcdesc}{pow}{x, y}
@@ -94,10 +102,11 @@ Return the tangent of \var{x}.
 Return the hyperbolic tangent of \var{x}.
 \end{funcdesc}
 
-Note that \code{frexp} and \code{modf} have a different call/return
+Note that \function{frexp()} and \function{modf()} have a different
-pattern than their C equivalents: they take a single argument and
+call/return pattern than their \C{} equivalents: they take a single
-return a pair of values, rather than returning their second return
+argument and return a pair of values, rather than returning their
-value through an `output parameter' (there is no such thing in Python).
+second return value through an `output parameter' (there is no such
+thing in Python).
 
 The module also defines two mathematical constants:
 

Doc/libmath.tex

@@ -4,7 +4,7 @@
 \bimodindex{math}
 \renewcommand{\indexsubitem}{(in module math)}
 This module is always available.
-It provides access to the mathematical functions defined by the C
+It provides access to the mathematical functions defined by the \C{}
 standard.
 They are:
 
@@ -25,7 +25,7 @@ Return \code{atan(\var{x} / \var{y})}.
 \end{funcdesc}
 
 \begin{funcdesc}{ceil}{x}
-Return the ceiling of \var{x}.
+Return the ceiling of \var{x} as a real.
 \end{funcdesc}
 
 \begin{funcdesc}{cos}{x}
@@ -45,7 +45,7 @@ Return the absolute value of the real \var{x}.
 \end{funcdesc}
 
 \begin{funcdesc}{floor}{x}
-Return the floor of \var{x}.
+Return the floor of \var{x} as a real.
 \end{funcdesc}
 
 \begin{funcdesc}{fmod}{x, y}
@@ -65,9 +65,17 @@ Return the Euclidean distance, \code{sqrt(\var{x}*\var{x} + \var{y}*\var{y})}.
 Return \code{\var{x} * (2**\var{i})}.
 \end{funcdesc}
 
+\begin{funcdesc}{log}{x}
+Return the natural logarithm of \var{x}.
+\end{funcdesc}
+
+\begin{funcdesc}{log10}{x}
+Return the base-10 logarithm of \var{x}.
+\end{funcdesc}
+
 \begin{funcdesc}{modf}{x}
 Return the fractional and integer parts of \var{x}.  Both results
-carry the sign of \var{x}.
+carry the sign of \var{x}.  The integer part is returned as a real.
 \end{funcdesc}
 
 \begin{funcdesc}{pow}{x, y}
@@ -94,10 +102,11 @@ Return the tangent of \var{x}.
 Return the hyperbolic tangent of \var{x}.
 \end{funcdesc}
 
-Note that \code{frexp} and \code{modf} have a different call/return
+Note that \function{frexp()} and \function{modf()} have a different
-pattern than their C equivalents: they take a single argument and
+call/return pattern than their \C{} equivalents: they take a single
-return a pair of values, rather than returning their second return
+argument and return a pair of values, rather than returning their
-value through an `output parameter' (there is no such thing in Python).
+second return value through an `output parameter' (there is no such
+thing in Python).
 
 The module also defines two mathematical constants: