Hi, maybe these below clarify a little bit the problem, but the problem sounds very intriguing http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2004-July/005729.html http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2005-October/006613.html http://cars9.uchicago.edu/ifeffit/FAQ/FeffitModeling I am waiting also for the answer from authors Do you see changes in the fit in R or/and K space, between systems? I suppose that all input parameters were identical... regards kicaj W dniu 12-03-10 15:17, Sameh Ibrahim Ahmed pisze:

Hi, I have used ARTEMIS to fit the EXAFS of a simple Cu foil with the two diffrent machines, a 32 bit and 64 bit ones, both running widows7, 32 ans 64 bit respectively. The results obtained are slightly different, I have appended the message with these results. the very low value of R-factor produced with the 64bit system is difficult to interpret. the questions are; 1- how to account for these differences? 2- if I to publish something, which measure of the quality should I present? and how can I interpret it? regards Sameh ============================================================ 32bit windows 7 Independent points = 12.172851562 Number of variables = 6.000000000 Chi-square = 53.001967099 Reduced Chi-square = 8.586301900 R-factor = 0.000163791 !!! Measurement uncertainty (k) = 0.000110566 Measurement uncertainty (R) = 0.057163282 Number of data sets = 1.000000000

Guess parameters +/- uncertainties (initial guess): amp = 0.9907500 +/- 0.0312520 (1.0000) enot = 5.6814210 +/- 0.3815760 (0.0000) delr1 = 0.0016460 +/- 0.0033990 (0.0000) ss1 = 0.0099820 +/- 0.0004090 (0.0030) w1 3rd cumulant = 0.0001710 +/- 0.0000340 (0.0000) p1 4th cumulant = 0.0000240 +/- 0.0000070 (0.0000)

============================================================ 64bit windows 7 Independent points = 12.172851562 Number of variables = 6.000000000 Chi-square = 54.036163164 Reduced Chi-square = 8.753841335 R-factor = 0.309664502E-06 !!! Measurement uncertainty (k) = 0.000097377 Measurement uncertainty (R) = 0.050344538 Number of data sets = 1.000000000

Guess parameters +/- uncertainties (initial guess): amp = 1.0029100 +/- 0.0296670 (1.0000) enot = 5.7522760 +/- 0.4614510 (0.0000) delr1 = 0.0024980 +/- 0.0040190 (0.0000) ss1 = 0.0101430 +/- 0.0003790 (0.0030) w1 3rd cumulant = 0.0001780 +/- 0.0000410 (0.0000) p1 4th cumulant = 0.0000260 +/- 0.0000070 (0.0000) ============================================================

_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit

Hi Sameh, On Sat, Mar 10, 2012 at 8:17 AM, Sameh Ibrahim Ahmed wrote:

Hi,

I have used ARTEMIS to fit the EXAFS of a simple Cu foil with the two diffrent machines, a 32 bit and 64 bit ones, both running widows7, 32 ans 64 bit respectively. The results obtained are slightly different, I have appended the message with these results. the very low value of R-factor produced with the 64bit system is difficult to interpret. the questions are; 1- how to account for these differences? 2- if I to publish something, which measure of the quality should I present? and how can I interpret it?

regards Sameh

============================================================ 32bit windows 7 Independent points = 12.172851562 Number of variables = 6.000000000 Chi-square = 53.001967099 Reduced Chi-square = 8.586301900 R-factor = 0.000163791 !!! Measurement uncertainty (k) = 0.000110566 Measurement uncertainty (R) = 0.057163282 Number of data sets = 1.000000000

Guess parameters +/- uncertainties (initial guess): amp = 0.9907500 +/- 0.0312520 (1.0000) enot = 5.6814210 +/- 0.3815760 (0.0000) delr1 = 0.0016460 +/- 0.0033990 (0.0000) ss1 = 0.0099820 +/- 0.0004090 (0.0030) w1 3rd cumulant = 0.0001710 +/- 0.0000340 (0.0000) p1 4th cumulant = 0.0000240 +/- 0.0000070 (0.0000)

============================================================ 64bit windows 7 Independent points = 12.172851562 Number of variables = 6.000000000 Chi-square = 54.036163164 Reduced Chi-square = 8.753841335 R-factor = 0.309664502E-06 !!! Measurement uncertainty (k) = 0.000097377 Measurement uncertainty (R) = 0.050344538 Number of data sets = 1.000000000

Guess parameters +/- uncertainties (initial guess): amp = 1.0029100 +/- 0.0296670 (1.0000) enot = 5.7522760 +/- 0.4614510 (0.0000) delr1 = 0.0024980 +/- 0.0040190 (0.0000) ss1 = 0.0101430 +/- 0.0003790 (0.0030) w1 3rd cumulant = 0.0001780 +/- 0.0000410 (0.0000) p1 4th cumulant = 0.0000260 +/- 0.0000070 (0.0000) ============================================================

Except for R-factor, these differences are pretty small -- all parameters are well within the estimated error bars. I'm not sure why R-factor is different. I would say that there is essentially no difference in what to report.... the R factors are both small enough to mean "very good fit", and any difference between them would really only important when comparing two different fits -- in that case, just be consistent. But that's not to say that it's not worth trying to understand the difference.... but that might take a bit of investigative work. One thing I noticed in the projects you sent (only to me -- please use the mailing list!!) is that these fits use different versions of Athena and ifeffit: 32bit Win7: Artemis 0.8.012, ifeffit 1.2.11 64bin Win7: Artemis 0.8.014, ifeffit 1.2.11c Off hand, I don't know that either of these is actually significant. --Matt