使用 dumb 模式直接得到 ASCII 图，这个 Gnuplot 真是太强大了

gnuplot> set term dumb
Terminal type set to 'dumb'
Options are 'feed 79 24'
gnuplot> set yrange [0:*]
gnuplot> set xrange [0:20]
gnuplot> set xtics 0,2,20
gnuplot> f(x) = 200*(1.1**x)
gnuplot> g(x) = 40*x
gnuplot> plot f(x), g(x)

1400 ++-----+-----+------+------+------+-----+------+------+-----+-----++
+ + + + + + + + +f(x) ********
| g(x) ####***|
1200 ++ *** ++
| *** |
| ** |
1000 ++ *** ++
| *** |
| *** |
800 ++ **** ######
| *** ###### |
600 ++ **** ###### ++
| **** ###### |
| ****** ##### |
400 ++ ***** ####### ++
| ******** ####### |
| ********** ###### |
200 ******** ###### ++
| ###### |
+ ###### + + + + + + + + +
0 ####---+-----+------+------+------+-----+------+------+-----+-----++
0 2 4 6 8 10 12 14 16 18 20