Dear All, Just wondering what could I do to make the amp guess value as a positive number? If I run it and let it float (i.e. guess), the amp becomes negative in the resulting fits, but the fit has nice delr and ss values (i.e. make sense). If I restrict the amp value to 1, everything else doesn't fit. I am only fitting the first nearest neighbour in a measured standard; Gadolinium oxide. Regards, Nic Nicholas Tse Postgraduate Student, University of Melbourne CSIRO Materials Science and Engineering. Phone: +61 3 9545 2626 | Mobile: 0403 782 805 nicholas.tse@csiro.aumailto:nicholas.tse@csiro.au | www.csiro.auhttp://www.csiro.au | www.csiro.au/cmsehttp://www.csiro.au/cmht Address: Ian Wark Laboratories, Bayview Ave Clayton 3169 VIC [Postal: Private Bag 10, Clayton South VIC 3169] [Deliveries: Gate 3 Normanby Road, Clayton VIC 3168] Please consider the environment before printing this email.