Gemeinsames Netzwerkzentrum (GNZ)  
der Berlin-Brandenburgischen Max-Planck-Einrichtungen  
Fritz-Haber-Institut der MPG e.V.  








- Filled Contours -
- Visualization of 2D-Arrays -
- Finding Maxima, Minima, and Saddle Points -

xfarbe - Fill Area with Bicubics

Main features

  • Running on Unix systems including Linux, source code provided
  • Nonlinear interpolation with bicubics on a rectangular grid
  • Computation of contour lines, piecewise in the rectangular cells
  • Area filling with colors and patterns between the contour lines
  • Location of maxima, minima and saddle points by bicubic interpolation
  • Estimation of second derivatives at those points (New in version 2.6)
  • Computation of uphill and downhill lines (Traverses) from any point
  • Output to X-displays and to Postscript files
  • Detailed customizing with X11 resource file
  • Interactive and automatic labeling of contour lines
  • Interactive data probing for value and derivatives
  • Placing of symbols according to information from a file
  • Computation of profiles across the rectangular grid


  • Screen dump
  • Postscript file
  • On the right side:
    • Surface with 2 saddle points, 1 Maximum x, 1 Minimum o
    • Surface with saddle points, and interactively generated
      uphill and downhill lines


The complete package (Version 2.6c)

The new feature in version 2.6 is the computation of the values of second derivatives in x and y added to the information about maxima, minima, and saddle points, which is written to the output file xfarbe.mms. These values will be scaled, if the scale for the axes is provided. That scale will now also be applied to other output information. I am grateful to E. Penev and S. Immel for suggesting these changes.


Please send comments, suggestions and bugs to

Thank you.

For editing the Postscript files produced by xfarbe, I recommend usage of Adobe Illustrator or xfig You can easily add text, change colors, etc.

I am interested to hear about any work in which xfarbe was helpful. If you have prepared a web page about your work, I would like to add a link to it from this page.

Here are some links for the beginning:

Heterogeneous Catalysis and Surface Thermodynamics, FHI, Berlin

Chemical Reactions at Surfaces: CO Oxidation, CMT, University of Sydney

Analytically defined Surfaces to analyzed molecular interaction Properties, European Molecular Biology Laboratory, Heidelberg

Biomolecular Electrostatics with the Linearized Poisson-Boltzmann Equation, Universities of Verona and Udine

Potential Energy surfaces for Disaccharides Structures, CERMAV-CNRS, Grenoble

Liquid-vapour oscillations, SANSOM GROUP, University of Oxford

Preusser 27.04.2007

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