set output 'square_ex_a4.ps' 
set term postscript color enhanced 'Helvetica,18'  
set style line 1 lt rgb 'red' lw 3  
set style line 2 lt rgb 'sea-green' lw 3  
set style line 3 lt rgb 'blue' lw 3  
set style line 4 lt rgb 'dark-orange' lw 3  
set style line 5 lt rgb 'violet' lw 3  
set grid 
set key top right 
set ylabel 'Value  '  
set xlabel 'Time (s)' 
set title 'f(t) = square wave ' 
set arrow 1 from 2,0 to 2,1 nohead ls 1 lw 6  
set arrow 2 from 4,0 to 4,1 nohead ls 1 lw 6  
set arrow 3 from 6,0 to 6,1 nohead ls 1 lw 6  
plot [0:8][-1.0:1.5] './test_four_b.out' index 0 using 2:4         with lines ls 1 lw 6 t ''  ,                         './test_four_b.out' index 0 using ($2+2):4         with lines ls 1 lw 6 t ''  ,                         './test_four_b.out' index 0 using ($2+4):4         with lines ls 1 lw 6 t ''  ,                         './test_four_b.out' index 0 using ($2+6):4         with lines ls 1 lw 6 t ''  
set output 
quit 
