Hi,
I'm not seeing the intended equation in the 'wls' reference, i.e. I
believe something must be wrong in doc/commands/gretl_commands_en.xml in
the part:
<equation status="display"
tex="\[R^2 = 1 - \frac{\rm ESS}{\rm WTSS}\]"
ascii="R^2 = 1 - ESS / WTSS"
graphic="wlsr2"/>
(line 14688...)
This is 2019a.
cheers
sven