start = 0
bio(day, cycle) =  sin((real(day-1+start)/cycle)*2*pi) * 100
set xlabel "Biorhythm Chart for 7/1955"
set xtics 1,1,31
plot [x=1:31] \
  bio(x,23) title 'Physical', \
  bio(x,28) title 'Emotional', \
  bio(x,33) title 'Intellectual'
pause -1 'Hit <return>'