On Monday 17 September 2007, Matthew Ginder-Vogel wrote:

When merging the energy scales of the various files, why did you choose to use a quadratic interpolation rather than a linear or spline interpolation?

Actually, you decide ;-) In the preferences: General->intrp.

Also, I notice that Athena sends a lot of commands that look like

set vpkr.energy = vpkr.energy+0 or set yybe.merge = qinterp(yybe.energy+0, yybe.xmu, vpkr.energy)

to IFEFFIT when merging files.

What does the +0 do at the end of the array? I've been looking through the IFEFFIT documentation, but can't seem to find anything that clarifies that command. Also, if I try and issue the command at the IFEFFIT command line I get an error that reads "** cannot set scalar value to array **". So why can Athena issue the command and I can't?

That would be because you are insufficiently cool ;-) "0" is actually the value of the energy shift from the main window in Athena. When I say in the Athena documentation that the energy shift is applied first and that the E0 value and all relative energy values are on the shifted energy grid -- I actually mean that I am careful to always add the energy shift whenever there is an Ifeffit command that takes an energy array. You should send a concise example of lines that give you the "** cannot set scalar value to array **". In principle, Ifeffit will add a scalar to a vector en passant. You shouldn't need to define a new array just to hold that sum. It might help to enclose the addition in quotation marks, i.e.: set yybe.merge = qinterp("yybe.energy+1", yybe.xmu, vpkr.energy) rather than set yybe.merge = qinterp(yybe.energy+1, yybe.xmu, vpkr.energy) (You probably also want to use nore mnemonic groups names that Athena's random four letter strings!) HTH, B -- Bruce Ravel ---------------------------------------------- bravel@anl.gov Molecular Environmental Science Group, Building 203, Room E-165 MRCAT, Sector 10, Advanced Photon Source, Building 433, Room B007 Argonne National Laboratory phone and voice mail: (1) 630 252 5033 Argonne IL 60439, USA fax: (1) 630 252 9793 My homepage: http://cars9.uchicago.edu/~ravel EXAFS software: http://cars9.uchicago.edu/~ravel/software/