Bandwidth:
By default gnuplot calculates and uses the bandwidth which would be optimal
for normally distributed data values.
default_bandwidth = sigma * (4/3N) ** (0.2)
plot $DATA smooth kdensity bandwidth <value> with boxes
Period:
For periodic data individual Gaussian components should be treated as repeating
at intervals of one period. One example is data measured as a function of
angle, where the period is 2pi. Another example is data indexed by day-of-year
and measured over multiple years, where the period is 365.
In such cases the period should be provided in the plot command:
plot $ANGULAR_DAT smooth kdensity period 2*pi with lines