File:AliasingSines.svg

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AliasingSines.svg‎ (SVG file, nominally 675 × 225 pixels, file size: 72 KB)

[edit] Summary

Description	AliasingSines.svg English: A graph showing aliasing of an f=0.9 sine wave by an f=0.1 sine wave by sampling at a period of T=1.0, based on the raster image AliasingSines.png. Français : Une graphique qui démontre le crénelage d'un signal sinusoïdal de fréquence f=0.9, confondu avec un signal de fréquence f=0.1 lors d'un échantillonnage de période T=1.0, basée sur l'image matricielle AliasingSines.png.
Date	21 April 2009(2009-04-21)
Source	Own work
Author	Moxfyre
Permission (Reusing this image)	See below.
Other versions	File:AliasingSines.png

[edit] Program code

Here is the Python code to produce this graph, using NumPy and Matplotlib:

#!/usr/bin/python2.5
 
from pylab import *
from numpy import *
 
# create a figure
figure(figsize=(7.5,2.5))
rcParams.update({"figure.subplot.left":0.05, "figure.subplot.right":0.95,
                 "figure.subplot.bottom":0.1, "figure.subplot.top":0.9,
                 "svg.embed_char_paths":False})
 
# x coords from -1 to 11
x_fine = linspace(-0.4, 10.4, 1000)
x_coarse = linspace(0, 10, 11)
 
# sinewave w/ freq=0.9
y1 = sin(2*pi * 0.9 * (x_fine-0.5))
plot( x_fine, y1, "-", color="red")
 
# sinewave w/ freq=0.1
y2 = sin(2*pi * 0.1 * (x_fine-0.5))
plot(x_fine, y2, "-", color="blue")
 
# show aliasing
y3 = sin(2*pi * 0.1 * (x_coarse-0.5))
plot( x_coarse, y3, "o", color="black" )
vlines( x_coarse, 0, y3, color="black" ) # add the "lollipop" points
 
# set window and tick labels
axis([-0.5, 10.5, -1.1, 1.1])
yticks((-1.0,0,1.0), ('',0,''))
xticks(linspace(0,10,11))
 
# save it
savefig("AliasingSines.svg", transparent=True)

[edit] Licensing

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
Subject to disclaimers.

This file is licensed under the Creative Commons Attribution ShareAlike 3.0 License. In short: you are free to share and make derivative works of the file under the conditions that you appropriately attribute it, and that you distribute it only under a license identical to this one. Official license Subject to disclaimers.

This licensing tag was added to this file as part of the GFDL licensing update.

This file is licensed under the Creative Commons Attribution ShareAlike 3.0 License. In short: you are free to share and make derivative works of the file under the conditions that you appropriately attribute it, and that you distribute it only under a license identical to this one. Official license

File history

Click on a date/time to view the file as it appeared at that time.

	Date/Time	Thumbnail	Dimensions	User	Comment
current	17:51, 21 April 2009		675×225 (72 KB)	Moxfyre (talk \| contribs)	(a better interpretation of the original PNG version as used in the w:en:Aliasing article)
	17:42, 21 April 2009		675×225 (46 KB)	Moxfyre (talk \| contribs)	(added "lollipop" points as in the .png version)
	17:29, 21 April 2009		675×225 (41 KB)	Moxfyre (talk \| contribs)	({{Information \|Description={{en\|1=A graph showing aliasing of an ''f=0.9'' w:sine wave by an ''f=0.1'' sine wave by sampling at a rate of 1.0, based on the raster image w:en:File:AliasingSines.png.}} \|Source=Own work by uploader \|Author=[[User)