set logscale <axes> {<base>} unset logscale <axes> show logscale
where <axes> may be any combinations of `x`, `x2`, `y`, `y2`, `z`, `cb`, and `r` in any order. <base> is the base of the log scaling (default is base 10). If no axes are specified, the command affects all axes except `r`. The command logscale turns off log scaling for all axes.
Examples:
To enable log scaling in both x and z axes:
set logscale xz
To enable scaling log base 2 of the y axis:
set logscale y 2
To enable z and color log axes for a pm3d plot:
set logscale zcb
To disable z axis log scaling:
unset logscale z