Dear Bruce, I am new in the list and really don't know if the points raised below were already discussed. In the (D)Artemis (Demeter version 0.9.13) how may I: - Plot different fits with the experimental data (to visually compare the results) - I don't know if this is a (new) bug of the program but when I try to restore a fit the program closes. In the log file the following line is written: "Can't use an undefined value as a HASH reference at C:/Strawberry/perl/site/lib/Demeter/Fit.pm line 1558." Obs.: I am running Demeter in Windows 7 (Pro). Another problem is related to the statistical errors when constraining the S0^2 parameter to float between two limits. The program doesn't return the error for all others parameters (but just zero as the error value) as you can see below: guess parameters: amp = 0.79284158 # +/- 0.00000000 [0.95] enot = 5.29826510 # +/- 0.00000000 [0] delrIn11 = 0.00235278 # +/- 0.00000000 [0] ssIn11 = 0.00155959 # +/- 0.00000000 [0.00300] delrCe1 = -0.00231455 # +/- 0.00000000 [0] ssCe1 = 0.00192778 # +/- 0.00000000 [0.00300] delrIn11In11 = 0.02070081 # +/- 0.00000000 [0] delrIr1 = -0.00435502 # +/- 0.00000000 [0] ssIr1 = 0.00386517 # +/- 0.00000000 [0.00300] delrIn31 = 0.00648507 # +/- 0.00000000 [0] ssIn31 = 0.00669602 # +/- 0.00000000 [0.00300] delrIn12 = 0.00255704 # +/- 0.00000000 [0] ssIn12 = 0.00305432 # +/- 0.00000000 [0.00300] def parameters: b = 0.80000000 # [min(max(0.8,amp),1.0)] Thanks so much in advance. Nilmar