set title "Spectrum of various samples of the function cos(6*pi*t)\nWith Frequency 6*pi = 18.85"
set xlabel "Frequecy"
set ylabel "Re(g(w))"
plot [x=0:42] [0:32] "four11.txt" every :::1::1 using 1:2  title "Once every second"  with linespoints, \
"four11.txt" every :::3::3 using 1:2 title "Once evey half second" with linespoints, \
"four11.txt" every :::5::5 using 1:2 title "Once evey quarter secon" with linespoints, \
"four11.txt" every :::7::7 using 1:2 title "Once evey eigth of a second" with linespoints, \
"four11.txt" every :::9::9 using 1:2 title "Once evey sixteenth of a second" with linespoints