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Graphical Reduction and Analysis SANS
Program for MatlabTM

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"GRASansP" is a MatlabTM script application designed for the graphical inspection, analysis and reduction of multi-detector data produced by the Small-Angle Neutron Scattering (SANS) instruments of the Institut Laue-Langevin (ILL).  GRASansP deals with many of the diverse requirements for analysis and reduction of SANS data using a general set of tools and reduction algorithms.  Data from the two ILL SANS instruments, D11 and D22, as well as SANS instruments at some other neutron sources, are currently catered for in the GRASansP package.  In principle the architecture and coding of GRASansP combined with the matrix handling abilities, graphics and other advantages of the Matlab™ environment should allow continued development of this software and be able to provide more general aspects of multi-detector and complex data set handling. The drive for producing such a suite of software came from the overwhelming need for a modern, complete and general-purpose package to deal with typical procedures required for analysis of two-dimensional SANS multidetector data.  By it’s very nature, two-dimensional data is often best appreciated in a graphical form.  The birth of GRASansP came from the need for graphical inspection and ability to be able to quickly process and extract the scattered intensity, I(q), as a function of position on the multidetector (qx,qy) or as a function of sample environment conditions from a series of many measurement runs (e.g. temperature sweep, rocking curve etc.).  This, combined with an interest in scientific software development and the abilities of the Matlab™ environment have brought GRASansP into it’s present state.


Key Features:

  • Modern, GUI oriented software suite.
  • Powerful graphical data display.
  • Emphasis on 2D multidetector data (anisotropic analysis).
  • Easy background and calibration corrections to data.
  • Easy analysis and re-grouping of run number sequences for measurements with varying sample environment conditions. e.g. rocking curves, temperature scans, TOF and kinetic measurements.
  • 1D and 2D Graphical Export (eps, jpg, bmp, etc.)
  • 1D and 2D Data Export (ASCII)

GRASansP is developing daily, responding to the needs, requests, bug-fixes, annoyances and frustrations noted by the growing number of SANS experimentalists who now are using, or at lest making a ‘test-drive’ of this new SANS data reduction software. Comments and suggestions for improvement are always welcome and should be e-mailed directly to me at dewhurst(at) Having said this, as a disclaimer, it should be stated that being the first release of GRASansP it is not impossible that bugs and quirks may appear during operation of this software. I am confident at this stage, however, that any mathematical operations performed on data sets during reduction are correct with a corresponding accuracy in the propagation of experimental errors associated with each data set. You ‘the user’ are instrumental in the continued development of GRASansP by reporting bugs or suggestions for improvement. Users are also encouraged to actively participate in the development of GRASansP by the contribution of ‘user modules’ to tailor GRASansP to the specific needs of the user and can be easily and almost seamlessly integrated into the general GRASansP interface without modification to the main code.


Author Information




by Charles Dewhurst

[email:  dewhurst(at)

Institut Laue Langevin





  • GRASansP  is freely available for use and user contribution for non-commercial purposes.
  • GRASansP  has been developed at the Institut Laue-Langevin (ILL) and remains copyright of the ILL.
  • GRASansP is provided free of charge, "as is", and with no warranty.

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Last Modified 09 January 2008 by C. D. Dewhurst