<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:Helvetica;
panose-1:2 11 6 4 2 2 2 2 2 4;}
@font-face
{font-family:Courier;
panose-1:2 7 4 9 2 2 5 2 4 4;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:"Lucida Calligraphy";
panose-1:3 1 1 1 1 1 1 1 1 1;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.apple-style-span
{mso-style-name:apple-style-span;}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>If your data is noisy, limits can also help keep the parameters from getting stuck in physically impossible local minima. For example, I might set a minimum FWHM to a little less than the narrowest peak my instrument can produce, then a few random points that happen to be above average cannot be mistaken for a peak.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Best regards,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Lucida Calligraphy";color:#1F497D'>William Boyer<o:p></o:p></span></p></div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> gsas-ii-bounces@aps.anl.gov [mailto:gsas-ii-bounces@aps.anl.gov] <b>On Behalf Of </b>Toby, Brian H.<br><b>Sent:</b> Monday, September 12, 2016 5:42 AM<br><b>To:</b> Ivo Alxneit <ivo.alxneit@psi.ch><br><b>Cc:</b> Von Dreele, Robert B. <vondreele@aps.anl.gov>; gsas-ii@mailman.aps.anl.gov<br><b>Subject:</b> Re: [GSAS-II] Can Parameters be restricted?<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>No. <o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>To be honest I am not sure why one would want to do this. When a parameter refines "out of range” it tells you something about your data or model. With a restraint, you would never know that for example, a Uiso value is refining negative by > 2 sigma or a occupancy is >>1. It makes sense to me to define a model so that the sum of occupancies is fixed — a well defined assumption. Defining a range for a parameter scares me as I could never know that my model is highly flawed is some way. <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Brian<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p><div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal>On Sep 12, 2016, at 10:27 AM, Ivo Alxneit <<a href="mailto:ivo.alxneit@psi.ch">ivo.alxneit@psi.ch</a>> wrote:<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>Dear all<br><br>is there a way to restrict fitted parameters to a certain range? For<br>example restrict site occupancies to positive numbers or to a range such<br>as 0.9-1.0?<br><br>thanks for any help<br>-- <br>Dr. Ivo Alxneit<br>Catalysis for Energy Group<br>Bioenergy and Catalysis Laboratory phone: +41 56 310 4092<br>Paul Scherrer Institute fax: +41 56 310 2688<br>CH-5232 Villigen gnupg key: 0x515E30C7<br>Switzerland<br><a href="https://www.psi.ch/ceg/catalysis-for-energy-group/">https://www.psi.ch/ceg/catalysis-for-energy-group/</a><br><br>_______________________________________________<br>GSAS-II mailing list<br><a href="mailto:GSAS-II@mailman.aps.anl.gov">GSAS-II@mailman.aps.anl.gov</a><br><a href="https://mailman.aps.anl.gov/mailman/listinfo/gsas-ii">https://mailman.aps.anl.gov/mailman/listinfo/gsas-ii</a><o:p></o:p></p></div></div></blockquote></div><p class=MsoNormal><o:p> </o:p></p><div><div><div><div><div><p class=MsoNormal><span class=apple-style-span><span style='font-size:9.0pt;font-family:Courier;color:black'>********************************************************************</span></span><span class=apple-style-span><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black'> </span></span><span class=apple-style-span><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black'><o:p></o:p></span></span></p><div><p class=MsoNormal><span style='font-size:9.0pt;font-family:Courier;color:black'>Brian H. Toby, Ph.D. office: 630-252-5488</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:9.0pt;font-family:Courier;color:black'>Advanced Photon Source Chief Computational Scientist</span><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.0pt;font-family:Courier;color:black'>Senior Physicist/Computational X-ray Science Group Leader</span><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.0pt;font-family:Courier;color:black'>9700 S. Cass Ave, Bldg. 401/B4192 cell: 630-327-8426 </span><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.0pt;font-family:Courier;color:black'>Argonne National Laboratory </span><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.0pt;font-family:Courier;color:black'>Argonne, IL 60439-4856 e-mail: brian dot toby at anl dot gov </span><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.0pt;font-family:Courier;color:black'>********************************************************************</span><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.0pt;font-family:Courier;color:black'>"</span><span class=apple-style-span><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black'>We will restore science to its rightful place, and wield technology's wonders... We will harness the sun and the winds and the soil to fuel our cars and run our factories... All this we can do. All this we will do."</span></span><span style='font-size:9.0pt;font-family:"Helvetica",sans-serif;color:black'><o:p></o:p></span></p></div></div></div></div></div></div><p class=MsoNormal><o:p> </o:p></p></div></div></div></body></html>