KnotPlot script for LewGanBru2

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.

• Go to:
• KnotPlot Site
• KnotPlot Download Site
• index of examples
• previous example
• next example

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 < LewGanBru2.kps

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

<LewGanBru2.kps

We now have the file LewGanBru2.eps which could be printed directly on a PostScript printer. For printing to a non-PostScript printer, generate a PDF file LewGanBru2.pdf from the EPS file LewGanBru2.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=LewGanBru2.pdf -c .setpdfwrite -f LewGanBru2.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, LewGanBru2.eps and LewGanBru2.pdf, as well as their counterparts for A4 paper, LewGanBru2_a4.eps and LewGanBru2_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=LewGanBru2.ppm -r200 -f LewGanBru2.eps
 
# scale it down using ImageMagick convert command
convert -resize 600x LewGanBru2.ppm LewGanBru2S.ppm
 
# reduce the number of distinct colours and create the gif
convert -colors 32 LewGanBru2S.ppm LewGanBru2.gif
 
# delete temporary files
/bin/rm LewGanBru2.ppm LewGanBru2S.ppm

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

% KnotPlot script: LewGanBru2.kps
% Sat 09 Mar 2019 01:48:53 UTC


% 119 crossing T(2,7) knot from paper by Lewin, Gan & Bruckstein
load LewGanBru2.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 LewGanBru2

% 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):

• LewGanBru2.pdf (36 kbytes)
• LewGanBru2_a4.pdf (36 kbytes)
• LewGanBru2.eps (69 kbytes)
• LewGanBru2_a4.eps (69 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).