KnotPlot script for PL

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 < PL.kps

We now have the file PL.eps which could be printed directly on a PostScript printer. For printing to a non-PostScript printer, generate a PDF file PL.pdf from the EPS file PL.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=PL.pdf -c .setpdfwrite -f PL.eps

The remainder of this example shows how the preview image seen above was created. This is only useful for including an image on a web page. Printing the EPS or PDF file will give much higher quality than printing the preview image. These files, PL.eps and PL.pdf, as well as their counterparts for A4 paper, PL_a4.eps and PL_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=PL.ppm -r200 -f PL.eps
 
# scale it down
pnmscale -xsize 600 PL.ppm > PLS.ppm
 
# reduce the number of distinct colours
ppmquant 32 PLS.ppm > PLSq.ppm
 
# create the GIF file
ppmtogif PLSq.ppm > PL.gif
 
# delete temporary files
/bin/rm PL.ppm PLS.ppm PLSq.ppm

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

% KnotPlot script: PL.kps
 
mode cb
cyl=.2
bead=.28
load ms/10.124
about z 90
 
psout PL
 
% 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):

• PL.pdf (8 kbytes)
• PL_a4.pdf (8 kbytes)
• PL.eps (15 kbytes)
• PL_a4.eps (15 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).