Bug 19673 reports that the documentation of clog10 is incorrect, both
failing to include the division by log (10) in the imaginary part and,
in the non-TeX version of the equation only, describing the LHS as log
rather than log10.
This patch fixes both issues. Note: I think it's appropriate that the
LHS says log10 not clog10, and that the cexp and clog descriptions
referred to in a comment in that bug report similarly say exp and log;
this is a mathematical description not a literal C one.
Tested for x86_64.
[BZ #19673]
* manual/math.texi (Exponents and Logarithms): Correct description
of clog10.