setytight

set ylim tight for the current values of xlim of a plot (xlim remains unchanged)

After setting xlim, it is sometimes useful to set ylim to range of the ydata within xlim. "axis tight" will set both xlim and ylim to the ranges of the full xdata and ydata.
setytight will leave xlim unaffected, and set ylim to the range of ydata within xlim.

For example:
plot(0:0.1:20,sin(0:0.1:20))
xlim([2 3])
setytight

setting xlim tight can be done with setxtight