[gnuplot] std with filledcurve 편차 예쁘게 그리기

https://stackoverflow.com/questions/25512006/gnuplot-smooth-confidence-interval-lines-as-opposed-to-error-bars

We need three cols for data: mean, low, high

# mean low high
   3   2.6  3.5
   5   4    6
   4   3.2  4.3




In script, you can use it 

set style fill transparent solid 0.2 noborder
plot 'data.d' u 1:2:3 w filledcurves t ''

Transparent는 eps모드에서 적용이 안되는 것 같다.