KnotPlot script for LewGanBru1

This page gives an example of a KnotPlot script that can be used to generate an Encapsulated PostScript (EPS) file. A bitmap preview of the EPS file is shown below. The EPS file is vector graphics, and is generally higher quality than the preview. To play with the KnotPlot script, you will need to download a copy of KnotPlot.

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Following is a detailed description on how the KnotPlot script was used to generate the files on this page. Example shown is for letter size paper. See the note (right) about printing to A4 paper. If you're only generating an EPS file for inclusion in another document, then you don't need to worry about setting the pagesize.

Run KnotPlot in non-graphics mode to generate the EPS file.

knotplot -nog < LewGanBru1.kps

One could instead run KnotPlot in graphics mode and enter the following command into the KnotPlot Command Window

<LewGanBru1.kps

We now have the file LewGanBru1.eps which could be printed directly on a PostScript printer. For printing to a non-PostScript printer, generate a PDF file LewGanBru1.pdf from the EPS file LewGanBru1.eps using Ghostscript.

# Note: enter the following three lines on one command line
gs -dCompatibilityLevel=1.3 -q -dNOPAUSE -dBATCH
   -sPAPERSIZE=letter -sDEVICE=pdfwrite
   -sOutputFile=LewGanBru1.pdf -c .setpdfwrite -f LewGanBru1.eps

The remainder of this example shows how the preview image seen above was created. This is useful for including an image on a web page or in a presentation. Printing the EPS or PDF file will give much higher quality than printing the preview image. These files, LewGanBru1.eps and LewGanBru1.pdf, as well as their counterparts for A4 paper, LewGanBru1_a4.eps and LewGanBru1_a4.pdf, can be downloaded using the links in the right hand panel on this page.

# run Ghostscript to generate a temporary PPM file
# Note: enter the following two lines on one command line
gs -q -dNOPAUSE -dBATCH -sPAPERSIZE=letter -sDEVICE=ppmraw
   -sOutputFile=LewGanBru1.ppm -r200 -f LewGanBru1.eps
 
# scale it down using ImageMagick convert command
convert -resize 600x LewGanBru1.ppm LewGanBru1S.ppm
 
# reduce the number of distinct colours and create the gif
convert -colors 32 LewGanBru1S.ppm LewGanBru1.gif
 
# delete temporary files
/bin/rm LewGanBru1.ppm LewGanBru1S.ppm

KnotPlot script that generated the Encapsulated PostScript (EPS) file:

% KnotPlot script: LewGanBru1.kps
% Sat 09 Mar 2019 01:48:27 UTC


% 111 crossing unknot from paper by Lewin, Gan & Bruckstein
load LewGanBru1.k
about z 90
fitto 42
psoption phantom "-32.33 -42 32.33 42"

% following two commands only relevant in graphics mode
scale = 0.1
dstep = 33

% refine the embedding using anchors
anchor
anch=t
ago 200

psoption font "/Helvetica"
psoption name    % put the name in the EPS file
psfscale = 12    % font scale in EPS file

psout LewGanBru1

% End of KnotPlot script

This script generates a EPS file (download below) suitable for printing on letter size paper. For printing on A4 size paper, use the command psop pagesize a4 prior to the psout command.

Download a high quality PDF or EPS file (for either letter or A4 size paper):

• LewGanBru1.pdf (42 kbytes)
• LewGanBru1_a4.pdf (42 kbytes)
• LewGanBru1.eps (80 kbytes)
• LewGanBru1_a4.eps (80 kbytes)

The PDF files and the preview image seen on this page were generated from the EPS files using Ghostscript (details in left panel on this page).