set samples <value>
The samples setting determines the number of values along the -axis at which functions are evaluated when they are plotted. For example:
set samples 100
causes 100 points to be evaluated. Increasing this value will cause functions to be plotted more smoothly, but also more slowly, and the postscript files generated will also be larger.
When functions are plotted with the points plot style, this setting controls the number of points plotted.