#!/bin/bash
# plotsine.sh
# A DEMO to display a sinewave inside a standard bash terminal.
# Issued as Public Domain, 2014, B.Walker, G0LCU.
# Device: Macbook Pro 13", OSX 10.7.5, default bash terminal.
# Use variables so that you can see how it works.
angle=0
step_angle=5
vert_plot=0
horiz_plot=5
centreline=12
amplitude=11
PI=3.14159
clear
# Do a single cycle, quantised graph.
while [ $angle -le 359 ]
do
	# Create each floating point value...
	# CygWin does not have the 'bc' command but it is now catered for... ;o)
	vert_plot=$(awk "BEGIN{ printf \"%.12f\", ((sin($angle*($PI/180))*$amplitude)+$centreline)}")
	# vert_plot=$(bc -l <<< "{print ((s($angle*($PI/180))*$amplitude)+$centreline)}")
	# Truncate the floating point value to an integer then invert the plot to suit the x y co-ordinates inside a terminal...
	vert_plot=$((24-${vert_plot/.*}))
	# Plot the point(s) and print the angle at that point...
	printf "\x1B["$vert_plot";"$horiz_plot"f*"
	printf "\x1B[22;1fAngle is $angle degrees... "
	sleep 0.1
	# Increment values...
	angle=$((angle+step_angle))
	horiz_plot=$((horiz_plot+1))
done
printf "\x1B[23;1fSinewave plotted as a quantised text mode graph.\n"
exit 0
# The results printed inside an 80 x 24 terminal window...
#
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#Angle is 355 degrees...                            ***         ***
#Sinewave plotted as a quantised text mode graph.      *********