On Wednesday 28 April 2004 05:20 am, Schmithals wrote:
I made a mistake in my previous posting: athenatest.zip contains two experimental files: exp01.dat and exp02.dat with a (slightly) different scaling. I read them in and exported to exp01.xmu and exp02.xmu. The values indeed correspond exactly to the original files. But if I import both groups to a single file then the scaling of the first group will be used for both and the ordinate data from exp02 will be changed accordingly. How is this done, linear interpolation?
Aha! I misunderstood the question. You are refering to the energy grid on which the data are written out. I had thought that by "scaling" you were refering somehow to the height along the y-axis. Yes -- when Athena exports many data groups in one file, it selects the energy grid of the first marked group (i.e. the one occupying the top-most position in the group list) as the standard and then interpolates each of the other groups onto that energy grid using Ifeffit qinterp() function. This interpolation is necessary for a file with a single energy column. FYI, Athena also interpolates when doing a merge and in any other situation where a common energy grid is called for.
Actually, I find this behaviour very useful: if I export many groups for display in an other program I can plot all of them versus the same abzissae-values. Is it possible to integrate that feature for export of single files as well? (as I now prefer that method because of the automatic parameter export).
Sort of. It is possible to interpolate data as it is imported to the energy grid of the standard using the pre-processing feature of the column selection dialog. However any kind of e0 shift, either by calibration or alignment, would undo that. Athena should allow you to interpolate a group onto the grid of another group at any time. I'll put that on the to do list. B -- Bruce Ravel ----------------------------------- ravel@phys.washington.edu Code 6134, Building 3, Room 405 Naval Research Laboratory phone: (1) 202 767 2268 Washington DC 20375, USA fax: (1) 202 767 4642 NRL Synchrotron Radiation Consortium (NRL-SRC) Beamlines X11a, X11b, X23b National Synchrotron Light Source Brookhaven National Laboratory, Upton, NY 11973 My homepage: http://feff.phys.washington.edu/~ravel EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/