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 OSF1

dxhangulim

dxhangulim(1X)															    dxhangulim(1X)

NAME

       dxhangulim - An input server for Korean

DESCRIPTION

       In  a  Motif environment such as CDE, Asian language input methods are supported by independent processes called input servers.	The Korean
       input server (dxhangulim) is an X client process that can run on a standard X server, provided that the	server	system	has  the  required
       Korean  fonts installed. This means that the Korean input server can run on any system that can access your X display device, including the
       device itself.

   Starting the Input Server
       If your CDE session language is set to Korean, the Korean input server is started automatically, and both  the  language  setting  and  the
       Korean  input  method  is available for applications that you start during that session. If your session language is not set to Korean, you
       can switch to Korean from a terminal emulation window by setting the LANG environment variable to a Korean locale. From the  same  terminal
       emulation  window, you must also use the command line to start the Korean input method server and then other applications in which you want
       to use Korean.

       You can start the input server on your local workstation by using the following command:

       % /usr/bin/X11/dxhangulim &

       If you want to start the input server on a remote system, log on the remote system, and enter the following commands. Substitute  the  name
       of your local system for <display_name> in the first command.

       % setenv DISPLAY <display_name>:0 % /usr/bin/X11/dxhangulim &

       After  the  input  server  is  started,	any Motif applications that have been internationalized to support Korean can communicate with the
       server to obtain input method services. However, remember that these applications must be started after the server is started.

   PC-Style Keyboard Restrictions
       If you are using a PC-style keyboard, the input server may not recognize the Backspace key as the way to delete the previous  character	in
       the input method preediting area. In this case, you must use the Delete key to delete the character.

       The default Alt-Space key sequence for activating and deactivating the input method may not work under CDE. In this case, invoke the dialog
       box for Input Method Customization and change the key sequence for Start Input Method and End Input Method to be something other than  Alt-
       Space. For example, you could change the sequence to be Ctrl-Space.

SEE ALSO

       Commands: dxhanziim(1X), dxhanyuim(1X), dxjim(1X), locale(1)

       Others: i18n_intro(5), Korean(5), l10n_intro(5)

																    dxhangulim(1X)