On Friday 13 April 2007 19:08, Victor.Streltsov@csiro.au wrote:
I am confused. I thought I did exactly what Bruce said. I added them in quadrature and used square root of that as the restraint in artemis: After summing in quadrature: restraint_sum = sqrt((restraint1)^2 + (restraint2)^2 + (restraint3)^2...)
I asked artemis "to build restraint from "restraint_sum"" and
artemis added line: res_restraint_sum=penalty(restraint_sum,n1,n2)*scale
This way of summing them seems closer to the way of adding them individually squared to the "vector to be minimized", provided artemis/ifeffit squares them before appending to the "vector" (you don't need to square them before). I guess the questions is what artemis does when asked to "build restraint from ..."?
"penalty" is just a normal ifeffit function. It is useful for making restraints, but has no special relationship to restraints. Use the sum in quadrature as *the* restraint, not as an argument of the penalty function. B -- Bruce Ravel ---------------------------------------------- bravel@anl.gov Molecular Environmental Science Group, Building 203, Room E-165 MRCAT, Sector 10, Advance 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/