Plotting A Sine Curve Inside A Bash Shell... Post: 302914568

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Operating Systems OS X (Apple) Plotting A Sine Curve Inside A Bash Shell... Post 302914568 by wisecracker on Tuesday 26th of August 2014 04:52:18 PM

08-26-2014

Registered User

Plotting A Sine Curve Inside A Bash Shell...

Hi all...

After mentioning the generation of a sinewave sweep generator in a previous thread in this forum this is the method I decided upon.

It plots a sinewave inside an 80 x 24 terminal window.
Although the original used bc (and the line is in the code but commented out) it is now changed to use awk as CygWin has NOT got "bc" in a default install.

It is __relatively__ simple now to create a swept frequency generator from 4 KHz to around 50 Hz and back using the default '/dev/dsp' mode for CygWin and/or 'aplay' or 'afplay' using a .WAV variant...

Enjoy finding simple solutions to often very difficult problems...

Code:

#!/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...
#
#                  *********
#               ***         ***
#              *               *
#            **                 **
#           *                     *
#          *                       *
#         *                         *
#        *                           *
#       *                             *
#      *                               *
#    **                                 **
#                                         *                                 *
#                                          *                               *
#                                           *                             *
#                                            *                           *
#                                             *                         *
#                                              *                       *
#                                               *                     *
#                                                **                 **
#                                                  *               *
#Angle is 355 degrees...                            ***         ***
#Sinewave plotted as a quantised text mode graph.      *********

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LEARN ABOUT DEBIAN

dpkg-www

DPKG-WWW(1)						      General Commands Manual						       DPKG-WWW(1)

NAME

       dpkg-www - program to remotely open a WWW Debian package browser

SYNOPSIS

       dpkg-www [-s|--stdout] [-h|--host host] [query]

DESCRIPTION

       dpkg-www is used to remotely control a WEB browser and open a dpkg URL on the local host from an interactive shell or script.

       If  the	command  is invoked while running under X-window the script will try to find an installed X browser to open the specified URL.	If
       not running under X it will try to use a text browser instead.

       If Netscape is found and a Netscape instance is already running it will be asked to open the dpkg URL on localhost with the optional  query
       supplied on the command line.  If there is no browser running, it will start automatically a new one.

       The  functionality  provided  by this program is identical to running a web browser with the -remote openURL(http://localhost/cgi-bin/dpkg)
       argument or opening the same URL from within the browser.

       dpkg-www-installer is an helper application which can configured in the WWW browser for	web  installation.  It	should	never  be  invoked
       directly by the user.

OPTIONS

       -s, --stdout
	      Redirect output to stdout. Requires one of the text browsers (lynx, lynx-ssl or links) installed.

       -h, --host host
	      Send the query to a remote host, where dpkg-www must be installed.

       query  Specifies  an  optional  package name, an absolute pathname or a query argument which is passed to the dpkg cgi-bin. See dpkg-www(8)
	      for more information about the use of the cgi.

FILES

       /etc/dpkg-www.conf

       ~/.dpkg-www
	      Configuration files for dpkg-www. It is not necessary for these files to exist, there are sensible defaults for everything, but  you
	      can specify your preferred www browser with the DPKG_WWW_BROWSER variable, for example: DPKG_WWW_BROWSER=mozilla

EXAMPLES

       dpkg-www
	      This would open a dpkg URL on localhost listing all the installed packages.

       dpkg-www bash
	      This would open a dpkg URL asking info on the bash package.

       dpkg-www -h pisolo bash
	      This would open a dpkg URL asking info on the bash package on host pisolo.

       dpkg-www 'dpkg*'
	      This would open a dpkg URL listing all packages matching dpkg*.

       dpkg-www /bin/bash
	      This would open a dpkg URL asking info on the package(s) owning the file /bin/bash .

       dpkg-www depends=svgalib
	      This would open a dpkg URL listing all packages depending on svgalib.

       dpkg-www --stdout depends=awk | grep ^ii
	      This would list on stdout all packages depending on awk and grep all lines of installed packages.

SEE ALSO

       dpkg(8), dpkg-www(8)

AUTHOR

       Massimo Dal Zotto <dz@debian.org>.
       Bugs should be reported via the normal Debian bug reporting system.

LICENCE

       dpkg-www is licensed under the GNU General Public License version 2.

								 September 1, 2004						       DPKG-WWW(1)