Integrating csch^2(x) gives an incorrect result



On Fri, 24 Jun 2011, Frazer Williams wrote:

> The error occurs when integrating (csch(x))^2.
>
>
>    (%i3) integrate((1/sinh(x))^2,x);
>                                           4
>    (%o3)                            -------------
>                                         - 2 x
>                                     2 %e      - 2
>
> According to a book of tables, the integral should be
>
>                    -coth x

The two only differ by an additive constant.  Maxima doesn't make the
constant of integration in an indefinite integral explicit.