官网 http://www.gnuplot.info/
首先输入：set term dumb 再次输入： 图形的命令，http://gnuplot.sourceforge.net/demo_5.0/simple.html
set term dumb set key right nobox set samples 100 plot [-pi/2:pi] cos(x),-(sin(x) > sin(x+1) ? sin(x) : sin(x+1))
gnuplot
原文：https://www.cnblogs.com/xiaoyii/p/10415295.html
