source: trunk/doc/expgui3.html @ 556

Last change on this file since 556 was 556, checked in by toby, 11 years ago

# on 2002/01/25 21:17:48, toby did:
add absorption & reorganize page

  • Property rcs:author set to toby
  • Property rcs:date set to 2002/01/25 21:17:48
  • Property rcs:lines set to +75 -32
  • Property rcs:rev set to 1.11
  • Property rcs:state set to Exp
  • Property svn:keywords set to Author Date Revision Id
File size: 10.1 KB
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1<html>
2<head>
3   <META NAME="Author" CONTENT="Brian H. Toby">
4   <title>EXPGUI</title>
5   <meta name="keywords" content="crystallography, Rietveld, diffraction,
6   GSAS, EXPGUI">
7</HEAD>
8<style>
9A:link {text-decoration:none}
10A:vlink {text-decoration:none}
11</style>
12
13<BODY BGCOLOR="#FFFFFF"
14      topmargin="0" leftmargin="0" marginwidth="0" marginheight="0" 
15      text="#000000" link="#0033ff" vlink="#0033ff" alink="#0033ff">
16
17<?
18   include("/var/www/include/navigation.inc");
19   include("/var/www/include/utility.inc");
20?>
21<blockquote><font face="arial, helvetica, sans-serif">
22
23<TABLE BORDER BGCOLOR="#FFFF40" ALIGN=RIGHT>
24<TR><TH><A  Href="expgui.html">EXPGUI top</A> 
25</TH><TH><A Href="expgui4.html">Next page</A>
26</TH><TH><A Href="expgui2.html">Previous page</A>
27</TH></TR></TABLE><BR CLEAR=ALL>
28
29<center><h1>
30<HR noshade width="75%" size="2" align="center">
31EXPGUI, part 3
32<HR noshade width="75%" size="2" align="center">
33</h1></center>
34<h3>A.3 Histogram pane</h3> 
35<DL><DL>
36The histogram pane is used to edit background
37and diffractometer constants for a histogram, as well as
38set damping and refinement flags for these parameters.
39<P>
40If
41<A href="expgui.html#multiplehistogram">
42"Multiple Histogram Selection" mode</A> is set to "All",
43this pane is disabled. For other settings of this mode,
44groups of histograms can be selected and modified
45collectively.
46<P>
47If the EXPTOOL program
48<A href="expgui.html#installation">(see the installation instructions)</A>
49is installed, a button for adding histograms will
50appear on the bottom right on this pane, as seen below. If the
51program is not properly installed, no errors occur, but the button
52does not appear.
53<P>
54Note that the order that histograms appear in this
55pane is determined by the <a href="expguic.html#sorthist">"Sort histograms by"</a> option in
56the Options Menu.
57</DL></DL>
58</blockquote>
59<img SRC="3.gif" align=TEXTTOP alt="EXPGUI Screen snapshot">
60<blockquote>
61<br clear=all>
62
63<a name="EditBackground"></a>
64<h3>A.3.1 Editing background</h3> 
65<DL><DL>
66<img SRC="3b1.gif" align=TEXTOP alt="EXPGUI Screen snapshot">
67When the button labeled "Edit Background", (or "Globally Edit Background"
68or in the case where <A href="expgui.html#multiplehistogram">
69"Multiple Histogram Selection" mode</A> is set to a single histogram type)
70is pressed, a window such as the one
71to the left is displayed. In the case where background coefficients
72are being edited for more than one histogram
73(<A href="expgui.html#multiplehistogram">
74"Multiple Histogram Selection" mode</A> must be
75set to a single histogram type) the entry boxes will appear blank
76and only those terms that are filled in will be changed when the "Set"
77button is pressed.
78This option is mostly useful when changing the background function or the
79number of terms for several histograms at a single time.
80Note that no changes are made until the "Set"
81button is pressed.
82<P>
83<IMG SRC="new.gif" HEIGHT=13 WIDTH=36 alt="New!">
84The "Fit Background Graphically" button is displayed only when a single
85histogram is selected for background editing. When this button is
86pressed, the <A HREF="liveplot.html#bkgedit">BKGEDIT</A> program is
87called to fit a background function to user-input fixed background points.
88See the <A HREF="liveplot.html#bkgedit">BKGEDIT documentation</A> for more
89information.
90</DL></DL>
91<br clear=all>
92
93<a name="EditAbsorption"></a>
94<h3>A.3.2 Editing absorption/reflectivity
95<IMG SRC="new.gif" HEIGHT=13 WIDTH=36 alt="New!">
96</h3> 
97<DL><DL>
98<img SRC="3h.gif" align=RIGHT alt="EXPGUI Screen snapshot">
99The refinement flag and damping factor for correction for absorption
100effects (or for flat-plate samples, reflectivity corrections) can be
101seen in a box near the bottom of the pane.
102The terms and the type of correction used
103are set using the "Edit Abs./Refl." button in this box. Pressing this
104button creates a window, shown to the right. A message is shown in the
105bottom of the window summarizing information about the selected correction.
106<P>
107<a name="AbsorptionSanity"></a>
108Please note, each correction is only appropriate for certain types of data
109and frequently the correction must be fixed rather than refined. It is
110wise to read the "Powder absorption factor" section of the GSAS manual
111(p 138-140 in 1/19/01 edition) before using this correction.
112Since some combinations of data types and correction types are unlikely --
113but not impossible
114(for example, a cylindical absorption correction and K-alpha1,2 radiation)
115EXPGUI will generate a warning message, such as the one below,
116but not all inappropriate actions can be prevented.
117The user must ultimately understand the role of the correction
118and the nature of the experiment to decide what is appropriate.
119<br clear=all>
120<img SRC="3h1.gif" align=TEXTTOP alt="EXPGUI Screen snapshot">
121<br clear=all>
122</DL></DL>
123<br clear=all>
124
125<a name="EditParm"></a>
126<h3>A.3.3 Global Editing of Parameters</h3> 
127<DL><DL>
128It is possible to access parameters and settings for more than one histogram
129at a time when a multiple selection of a specific histogram type
130is allowed
131(see
132<A href="expgui.html#multiplehistogram">
133"Multiple Histogram Selection" mode</A>).
134In this mode, the histogram pane
135appears slightly differently, as is shown below.
136</DL></DL>
137</blockquote>
138<img SRC="3c.gif" align=TEXTTOP alt="EXPGUI Screen snapshot">
139<blockquote>
140<br clear=all>
141<DL><DL>
142<img SRC="3d.gif" align=LEFT alt="EXPGUI Screen snapshot">
143Pressing a refinement flag checkbox will set all
144selected histogram refinement flags either off or on.
145Pressing a "Globally Edit..." button, will allow a parameter to be set.
146For example, the window to the left shows how
147a diffractometer constant can be
148edited for more than one histogram
149<P>
150A similar window is also used to globally set the
151<A href="expgui4.html">Phase Fraction</A> in
152<A href="expgui.html#multiplehistogram">
153"Multiple Histogram Selection"</A> mode.
154<br clear=all>
155
156</DL></DL>
157
158<a name="AddHist"></a>
159<h3>A.3.4 Entering New Diffractograms</h3> 
160<DL><DL>
161<img SRC="3e.gif" align=RIGHT alt="EXPGUI Screen snapshot">
162Pressing the "Add New Histogram" button creates the dialog
163to the left. This can be used to select diffraction data to be used
164in the refinement, or if the "dummy histogram" boxed is selected,
165a set of diffraction data can be simulated.
166<P>
167In the case where diffraction data will be input,
168a data file and an instrument parameter file must be
169selected using the "Select File" buttons. The limit for reflection
170generation (maximum energy or two-theta, or minimum d-space or TOF)
171must be entered, as well as the units.
172If more than one bank is defined, either in the data file or in the
173instrument parameter file, the bank must be selected as well.
174Note that the data range can be edited at a later time using the
175<a href="excledt.html">EXCLEDT</a> utility.
176<P>
177To view a plot of a data file, so that the range of the data
178may be viewed, the RAWPLOT program may be invoked using the "Run RAWPLOT"
179button. Note that EXPGUI cannot communicate the names
180of the data and instrument parameter files to RAWPLOT, so they must be
181reentered.
182<P>
183<br clear=all>
184<img SRC="3e1.gif" align=RIGHT alt="EXPGUI Screen snapshot">
185When the dummy histogram option is selected, diffraction data can
186be simulated based a set of experimental constants
187described in an instrument parameter file.
188Note that most of these instrumental parameters,
189such as wavelength or DIFC can be edited on this pane or
190on the <A HREF="expgui5.html">profile</A> pane
191(the simulated pattern is also affected by constants on the
192<A HREF="expgui4.html">scaling</A> pane.)
193The 2-theta/energy/TOF
194range to be used for the computation, as well as the step size,
195must be entered before pressing the "Add" button.
196Note that once the histogram is added, this range and step size
197cannot be edited within EXPGUI at present. However,
198EXPEDT can be used to change these values.
199<br clear=all>
200<P>
201<a name="AddHistErr"></a>
202<img SRC="3e2.gif" align=LEFT alt="EXPGUI Screen snapshot">
203If errors are detected in the input, an error message is displayed
204detailing where the errors are found. Otherwise, the EXPTOOL program is run
205and the output is optionally displayed
206(See <a href="expguic.html#exptoolout">Show EXPTOOL output</a>).
207</DL></DL>
208<br clear=all>
209<P>
210<h3>A.3.5 Editing the Data Range & Excluded Regions</h3> 
211<DL><DL>
212The button at the bottom of the pane, labeled
213"Set Data Limits & Excluded Regions" invokes
214the <a href="excledt.html">EXCLEDT</a> utility, which is used to
215modify the lower and upper data limits and can be used to add or delete
216excluded regions.
217</DL></DL>
218
219<h3>A.3.6 Setting Histogram Flags</h3> 
220<DL><DL>
221<img SRC="3f.gif" align=RIGHT alt="EXPGUI Screen snapshot">
222The button at the bottom of the pane, labeled "Set Histogram Use Flags" invokes
223a menu where the "Use"/"Do not use" flag for powder histogram can be set.
224When this flag is turned off, the histogram is ignored for
225subsequent computations, effectively removing from the experiment.
226<P>
227When these "Use" flags are changed, it is necessary to run POWPREF,
228to propogate the changes. After the "Save" button is pressed, a prompt such
229as the example below, is generated to run POWPREF. Note that GENLES may
230fail if POWPREF is not run after changing these flags.
231<br clear=all>
232<P>
233<img SRC="3g.gif" align=TEXTTOP alt="EXPGUI Screen snapshot">
234<br clear=all>
235</DL></DL>
236
237<h3>A.3.7 Setting Phase Flags</h3> 
238<DL><DL>
239If there is more than one phase present in the refinement,
240an extra box appears at the top of the pane to allow phase flags
241to be selected. This allows a phase to be used in some histograms
242but not in others. It also offers a simple way to effectively "delete" a
243phase by removing it from all histograms. Be sure to rerun POWPREF after
244changing the phase flags.
245</DL></DL>
246</blockquote>
247<img SRC="3a.gif" align=TEXTTOP alt="EXPGUI Screen snapshot">
248<blockquote>
249<br clear=all>
250<hr>
251<TABLE BORDER BGCOLOR="#FFFF40" ALIGN=RIGHT>
252<TR><TH><A  Href="expgui.html">EXPGUI top</A> 
253</TH><TH><A Href="expgui4.html">Next page</A>
254</TH><TH><A Href="expgui2.html">Previous page</A>
255</TH></TR></TABLE>
256
257<a href="http://www.ncnr.nist.gov/staff/toby/">Brian Toby</a> (<a href="mailto:brian.toby@nist.gov">Brian.Toby@NIST.GOV</a>)
258<br>
259$Revision: 556 $ $Date: 2009-12-04 23:08:09 +0000 (Fri, 04 Dec 2009) $
260</blockquote>
261</body>
262</html>
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