source: sasview/src/sas/sasgui/perspectives/fitting/media/fitting_help.rst @ 1b82623

ESS_GUIESS_GUI_DocsESS_GUI_batch_fittingESS_GUI_bumps_abstractionESS_GUI_iss1116ESS_GUI_iss879ESS_GUI_iss959ESS_GUI_openclESS_GUI_orderingESS_GUI_sync_sascalccostrafo411magnetic_scattrelease-4.1.1release-4.1.2release-4.2.2ticket-1009ticket-1094-headlessticket-1242-2d-resolutionticket-1243ticket-1249ticket885unittest-saveload
Last change on this file since 1b82623 was 05829fb, checked in by Paul Kienzle <pkienzle@…>, 8 years ago

document sasmodels plugin format

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[ec392464]1.. fitting_help.rst
2
3.. This is a port of the original SasView html help file to ReSTructured text
4.. by S King, ISIS, during SasView CodeCamp-III in Feb 2015.
5
[98b30b4]6.. |inlineimage004| image:: sm_image004.gif
7.. |inlineimage005| image:: sm_image005.gif
8.. |inlineimage008| image:: sm_image008.gif
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11.. |inlineimage011| image:: sm_image011.gif
12.. |inlineimage012| image:: sm_image012.gif
13.. |inlineimage018| image:: sm_image018.gif
14.. |inlineimage019| image:: sm_image019.gif
15
[ec392464]16
[b64b87c]17Fitting
18=======
[ec392464]19
[a6f3613]20.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
21
22Preparing to fit data
23---------------------
24
25To fit some data you must first load some data, activate one or more data sets,
[b64b87c]26send those data sets to fitting, and select a model to fit to each data set.
[a6f3613]27
[f3377b8]28Instructions on how to load and activate data are in the section :ref:`Loading_data`.
[ec392464]29
[a6f3613]30SasView can fit data in one of three ways:
[ec392464]31
[a6f3613]32*  in *Single* fit mode - individual data sets are fitted independently one-by-one
[ec392464]33
[f3377b8]34*  in *Simultaneous* fit mode - multiple data sets are fitted simultaneously to the *same* model with/without constrained parameters (this might be useful, for example, if you have measured the same sample at different contrasts)
[ec392464]35
[f3377b8]36*  in *Batch* fit mode - multiple data sets are fitted sequentially to the *same* model (this might be useful, for example, if you have performed a kinetic or time-resolved experiment and have *lots* of data sets!)
[a6f3613]37
38.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
[ec392464]39
[a6f3613]40Selecting a model
41-----------------
[ec392464]42
[a6f3613]43By default, the models in SasView are grouped into five categories
[ec392464]44
[a6f3613]45*  *Shapes* - models describing 'objects' (spheres, cylinders, etc)
[f3377b8]46*  *Shape-Independent* - models describing structure in terms of density correlation functions, fractals, peaks, power laws, etc
[8570246]47*  *Customized Models* - SasView- or User-created (non-library) Python models
[a6f3613]48*  *Uncategorised* - other models (for reflectivity, etc)
49*  *Structure Factor* - S(Q) models
[ec392464]50
[a6f3613]51Use the *Category* drop-down menu to chose a category of model, then select
[f3377b8]52a model from the drop-down menu beneath. A graph of the chosen model, calculated
53using default parameter values, will appear. The graph will update dynamically
54as the parameter values are changed.
55
56You can decide your own model categorizations using the :ref:`Category_Manager`.
[ce62e75]57
[a6f3613]58Once you have selected a model you can read its help documentation by clicking
59on the *Description* button to the right.
60
61Show 1D/2D
62^^^^^^^^^^
63
64Models are normally fitted to 1D (ie, I(Q) vs Q) data sets, but some models in
65SasView can also be fitted to 2D (ie, I(Qx,Qy) vs Qx vs Qy) data sets.
66
67*NB: Magnetic scattering can only be fitted in SasView in 2D.*
68
69To activate 2D fitting mode, click the *Show 2D* button on the *Fit Page*. To
70return to 1D fitting model, click the same button (which will now say *Show 1D*).
[ce62e75]71
[ec392464]72.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
73
[a6f3613]74.. _Category_Manager:
[a0637de]75
[a6f3613]76Category Manager
77----------------
78
[f3377b8]79To change the model categorizations, either choose *Category Manager* from the
80*View* option on the menubar, or click on the *Modify* button on the *Fit Page*.
[a6f3613]81
[f3377b8]82.. image:: cat_fig0.bmp
[a6f3613]83
[f3377b8]84The categorization of all models except the customized models can be reassigned,
85added to, and removed using *Category Manager*. Models can also be hidden from view
86in the drop-down menus.
[a6f3613]87
[f3377b8]88.. image:: cat_fig1.bmp
[a6f3613]89
[f3377b8]90Changing category
91^^^^^^^^^^^^^^^^^
[a6f3613]92
[f3377b8]93To change category, highlight a model in the list by left-clicking on its entry and
94then click the *Modify* button. Use the *Change Category* panel that appears to make
95the required changes.
[a6f3613]96
[f3377b8]97.. image:: cat_fig2.bmp
[a6f3613]98
[f3377b8]99To create a category for the selected model, click the *Add* button. In order
100to delete a category, select the category name and click the *Remove Selected*
101button. Then click *Done*.
[a6f3613]102
[f3377b8]103Showing/hiding models
104^^^^^^^^^^^^^^^^^^^^^
[a6f3613]105
[8570246]106Use the *Enable All / Disable All* buttons and the check boxes beside each model to
[f3377b8]107select the models to show/hide. To apply the selection, click *Ok*. Otherwise click
108*Cancel*.
[a6f3613]109
[8570246]110*NB: It may be necessary to change to a different category and then back again*
[f3377b8]111*before any changes take effect.*
[a6f3613]112
113.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
114
[f3377b8]115Model Functions
116---------------
[a6f3613]117
[20846be]118For a complete list of all the library models available in SasView, see the Model Documentation.
[a6f3613]119
[f3377b8]120It is also possible to add your own models.
[a6f3613]121
[f3377b8]122.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
[a6f3613]123
[b5846a10]124.. _Adding_your_own_models:
125
[f3377b8]126Adding your own models
127----------------------
[a6f3613]128
[f3377b8]129There are currently two ways to add your own models to SasView:
130
[8570246]131* Using the :ref:`Custom_Model_Editor`
132* By :ref:`Writing_a_Plugin`
[f3377b8]133
[a6f3613]134.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
135
[f3377b8]136.. _Custom_Model_Editor:
137
[a6f3613]138Custom Model Editor
139-------------------
140
[f3377b8]141From the *Fitting* option in the menu bar, select *Edit Custom Model*.
[a6f3613]142
143.. image:: edit_model_menu.bmp
144
[f3377b8]145and then one of the options
146
147*  *New* - to create a new custom model template
148*  *Sum|Multi(p1,p2)* - to create a new model by summing/multiplying existing models in the model library
149*  *Advanced* - to edit a new custom model
150*  *Delete* - to delete a custom model
[a6f3613]151
[f3377b8]152New
153^^^^
[a6f3613]154
155.. image:: new_model.bmp
156
[f3377b8]157A model template generated by this option can be viewed and further modified using
158the :ref:`Advanced` option.
159
[05829fb]160*NB: "Fit Parameters" has been split into two sections, those which can be
161polydisperse (shape and orientation parameters) and those which are not
162(scattering length densities, for example).*
163
[a6f3613]164Sum|Multi(p1,p2)
165^^^^^^^^^^^^^^^^
166
167.. image:: sum_model.bmp
[a0637de]168
[f3377b8]169This option creates a custom model of the form
170
[8570246]171Custom Model = scale_factor \* (model1 +/\* model2)
[f3377b8]172
173In the *Easy Sum/Multi Editor* give the new custom model a function name and brief
174description (to appear under the *Details* button on the *Fit Page*). Then select
175two existing models, as p1 and p2, and the required operator, '+' or '*' between
176them. Finally, click the *Apply* button to generate the model and then click *Close*.
177
178*NB: Any changes to a custom model generated in this way only become effective after*
179*it is re-selected from the model drop-down menu on the Fit Page.*
180
181.. _Advanced:
182
[a6f3613]183Advanced
184^^^^^^^^
[ec392464]185
[f3377b8]186Selecting this option shows all the custom models in the plugin model folder
187
[8570246]188  *C:\\Users\\[username]\\.sasview\\plugin_models* - (on Windows)
[f3377b8]189
190You can edit, modify, and save the Python code in any of these models using the
191*Advanced Custom Model Editor*.
192
[05829fb]193See :ref:`Writing_a_Plugin` for details on the plugin format.
194
195*NB: Sum/Product models are still using the SasView 3.x model format.  Unless
196you are confident about what you are doing, it is recommended that you
197only modify lines denoted with the ## <----- comments!*
[f3377b8]198
199When editing is complete, select *Run -> Compile* from the *Model Editor* menu bar. An
200*Info* box will appear with the results of the compilation and model unit tests. The
201model will only be usable if the tests 'pass'.
202
203To use the model, go to the relevant *Fit Page*, select the *Customized Models*
204category and then select the model from the drop-down menu.
205
206*NB: Any changes to a custom model generated in this way only become effective after*
207*it is re-selected from the model drop-down menu on the Fit Page.*
[a6f3613]208
209Delete
210^^^^^^
211
[f3377b8]212Simply highlight the custom model to be removed. This operation is final!
213
214*NB: Custom models shipped with SasView cannot be removed in this way.*
[ec392464]215
216.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
217
[4666660]218.. _Fitting_Options:
219
[f3377b8]220Fitting Options
221---------------
[a6f3613]222
[f3377b8]223It is possible to specify which optimiser SasView should use to fit the data, and
224to modify some of the configurational parameters for each optimiser.
225
226From *Fitting* in the menu bar select *Fit Options*, then select one of the following
227optimisers:
[a6f3613]228
[f3377b8]229*  DREAM
230*  Levenberg-Marquardt
231*  Quasi-Newton BFGS
232*  Differential Evolution
233*  Nelder-Mead Simplex
[a6f3613]234
[6af2785]235The DREAM optimiser is the most sophisticated, but may not necessarily be the best
236option for fitting simple models. If uncertain, try the Levenberg-Marquardt optimiser
237initially.
238
[f3377b8]239These optimisers form the *Bumps* package written by P Kienzle. For more information
[4666660]240on each optimiser, see the :ref:`Fitting_Documentation`.
[a6f3613]241
[f3377b8]242.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
[a6f3613]243
[5ac0a7a]244Fitting Limits
245--------------
246
247By default, *SasView* will attempt to model fit the full range of the data; ie,
248across all *Q* values. If necessary, however, it is possible to specify only a
249sub-region of the data for fitting.
250
251In a *FitPage* or *BatchPage* change the *Q* values in the *Min* and/or *Max*
252text boxes. Vertical coloured bars will appear on the graph with the data and
253'theory' indicating the current *Q* limits (red = *Qmin*, purple = *Qmax*).
254
255To return to including all data in the fit, click the *Reset* button.
256
257.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
258
259
[f3377b8]260Shortcuts
261---------
[a6f3613]262
[f3377b8]263Copy/Paste Parameters
264^^^^^^^^^^^^^^^^^^^^^
[a6f3613]265
[f3377b8]266It is possible to copy the parameters from one *Fit Page* and to paste them into
267another *Fit Page* using the same model.
[a6f3613]268
[f3377b8]269To *copy* parameters, either:
[a6f3613]270
[f3377b8]271*  Select *Edit -> Copy Params* from the menu bar, or
272*  Use Ctrl(Cmd on Mac) + Left Mouse Click on the *Fit Page*.
[a6f3613]273
[f3377b8]274To *paste* parameters, either:
275
276*  Select *Edit -> Paste Params* from the menu bar, or
277*  Use Ctrl(Cmd on Mac) + Shift + Left-click on the *Fit Page*.
278
279If either operation is successful a message will appear in the info line at the
280bottom of the SasView window.
281
282Bookmark
283^^^^^^^^
[a6f3613]284
[1fda506]285To *Bookmark* a *Fit Page* either:
[a6f3613]286
[f3377b8]287*  Select a *Fit Page* and then click on *Bookmark* in the tool bar, or
288*  Right-click and select the *Bookmark* in the popup menu.
[a6f3613]289
290.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
291
[4666660]292.. _Status_bar:
293
[1fda506]294Status Bar & Console
295--------------------
296
297The status bar is located at the bottom of the SasView window and displays
298messages, hints, warnings and errors.
299
300At the right-hand side of the status bar is a button marked *Console*. The *Console*
301displays available message history and some run-time traceback information.
302
303During a long task the *Console* can also be used to monitor the progress.
304
305.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
306
[6af2785]307.. _Single_Fit_Mode:
308
[a6f3613]309Single Fit Mode
310---------------
[ec392464]311
[4666660]312*NB: Before proceeding, ensure that the Single Mode radio button at the bottom of*
313*the Data Explorer is checked (see the section* :ref:`Loading_data` *).*
314
[63d314b]315This mode fits one data set.
316
[b64b87c]317When data is sent to the fitting it is plotted in a graph window as markers.
[4666660]318
319If a graph does not appear, or a graph window appears but is empty, then the data
320has not loaded correctly. Check to see if there is a message in the :ref:`Status_Bar`
321or in the *Console* window.
322
323Assuming the data has loaded correctly, when a model is selected a green model
324calculation (or what SasView calls a 'Theory') line will appear in the earlier graph
325window, and a second graph window will appear displaying the residuals (the
326difference between the experimental data and the theory) at the same X-data values.
[f9250dc]327See :ref:`Assessing_Fit_Quality`.
[4666660]328
329The objective of model-fitting is to find a *physically-plausible* model, and set
330of model parameters, that generate a theory that reproduces the experimental data
331and gives residual values as close to zero as possible.
332
333Change the default values of the model parameters by hand until the theory line
334starts to represent the experimental data. Then uncheck the tick boxes alongside
335all parameters *except* the 'background' and the 'scale'. Click the *Fit* button.
336SasView will optimise the values of the 'background' and 'scale' and also display
337the corresponding uncertainties on the optimised values.
338
339*NB: If no uncertainty is shown it generally means that the model is not very*
340*dependent on the corresponding parameter (or that one or more parameters are*
341*'correlated').*
342
343In the bottom left corner of the *Fit Page* is a box displaying the normalised value
344of the statistical |chi|\  :sup:`2` parameter returned by the optimiser.
345
346Now check the box for another model parameter and click *Fit* again. Repeat this
347process until most or all parameters are checked and have been optimised. As the
348fit of the theory to the experimental data improves the value of 'chi2/Npts' will
349decrease. A good model fit should easily produce values of 'chi2/Npts' that are
[ff42a26]350close to zero, and certainly <100. See :ref:`Assessing_Fit_Quality`.
[4666660]351
352SasView has a number of different optimisers (see the section :ref:`Fitting_Options`).
353The DREAM optimiser is the most sophisticated, but may not necessarily be the best
354option for fitting simple models. If uncertain, try the Levenberg-Marquardt optimiser
355initially.
[ec392464]356
357.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
358
[a6f3613]359Simultaneous Fit Mode
360---------------------
[ec392464]361
[63d314b]362*NB: Before proceeding, ensure that the Single Mode radio button at the bottom of*
363*the Data Explorer is checked (see the section* :ref:`Loading_data` *).*
[ec392464]364
[6af2785]365This mode is an extension of the :ref:`Single_Fit_Mode` that fits two or more data
[63d314b]366sets *to the same model* simultaneously. If necessary it is possible to constrain
367fit parameters between data sets (eg, to fix a background level, or radius, etc).
368
[b5846a10]369If the data to be fit are in multiple files, load each file, then select each file
370in the *Data Explorer*, and *Send To Fitting*. If multiple data sets are in one file,
371load that file, *Unselect All Data*, select just those data sets to be fitted, and
372*Send To Fitting*. Either way, the result should be that for *n* data sets you have
[6af2785]3732\ *n* graphs (*n* of the data and model fit, and *n* of the resulting residuals). But
[f9250dc]374it may be helpful to minimise the residuals plots for clarity. Also see
375:ref:`Assessing_Fit_Quality`.
[b5846a10]376
377*NB: If you need to use a customized model, you must ensure that model is available*
378*first (see* :ref:`Adding_your_own_models` *).*
379
[6af2785]380Method
381^^^^^^
382
[b5846a10]383Now go to each *FitPage* in turn and:
384
385  Select the required category and model;
386
387  Unselect all the model parameters;
388
389  Enter some starting guesses for the parameters;
390
391  Enter any parameter limits (recommended);
[63d314b]392
[b5846a10]393  Select which parameters will refine (selecting all is generally a bad idea...);
[63d314b]394
[b5846a10]395When done, select *Constrained or Simultaneous Fit* under *Fitting* in the menu bar.
396
397In the *Const & Simul Fit* page that appears, select which data sets are to be
398simultaneously fitted (this will probably be all of them or you would not have loaded
399them in the first place!).
400
401To tie parameters between the data sets with constraints, check the 'yes' radio button
402next to *Add Constraint?* in the *Fit Constraints* box.
403
404*NB: You can only constrain parameters that are set to refine.*
405
406When ready, click the *Fit* button on the *Const & Simul Fit* page, NOT the *Fit*
407button on the individual *FitPage*'s.
[63d314b]408
409Simultaneous Fits without Constraints
410^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[ec392464]411
[b5846a10]412The results of the model-fitting will be returned to each of the individual
413*FitPage*'s.
[ec392464]414
[b5846a10]415Note that the chi2/Npts value returned is the SUM of the chi2/Npts of each fit. To
[6af2785]416see the chi2/Npts value for a specific *FitPage*, click the *Compute* button at the
[f9250dc]417bottom of that *FitPage* to recalculate. Also see :ref:`Assessing_Fit_Quality`.
[ec392464]418
[63d314b]419Simultaneous Fits with Constraints
420^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[ec392464]421
[b5846a10]422Use the *Easy Setup* drop-down buttons in the *Const & Simul Fit* page to set
423up constraints between *FitPage*'s.
424
[6af2785]425Constraints will generally be of the form
426
427  Mi Parameter1 = Mj.Parameter1
428
429however the text box after the '=' sign can be used to adjust this
430relationship; for example
431
432  Mi Parameter1 = scalar \* Mj.Parameter1
433
434A 'free-form' constraint box is also provided.
[b5846a10]435
436Many constraints can be entered for a single fit.
437
438The results of the model-fitting will be returned to each of the individual
439*FitPage*'s.
[ec392464]440
[b5846a10]441Note that the chi2/Npts value returned is the SUM of the chi2/Npts of each fit. To
[6af2785]442see the chi2/Npts value for a specific *FitPage*, click the *Compute* button at the
[f9250dc]443bottom of that *FitPage* to recalculate. Also see :ref:`Assessing_Fit_Quality`.
[ec392464]444
445.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
446
[a6f3613]447Batch Fit Mode
448--------------
[ec392464]449
[6af2785]450*NB: Before proceeding, ensure that the Single Mode radio button at the bottom of*
451*the Data Explorer is checked (see the section* :ref:`Loading_data` *). The Batch*
452*Mode button will be used later on!*
[63d314b]453
[6af2785]454This mode *sequentially* fits two or more data sets *to the same model*. Unlike in
455simultaneous fitting, in batch fitting it is not possible to constrain fit parameters
456between data sets.
[ec392464]457
[6af2785]458If the data to be fit are in multiple files, load each file in the *Data Explorer*.
459If multiple data sets are in one file, load just that file. *Unselect All Data*, then
460select a single initial data set to be fitted. Fit that selected data set as described
461above under :ref:`Single_Fit_Mode` .
[ec392464]462
[6af2785]463*NB: If you need to use a customized model, you must ensure that model is available*
464*first (see* :ref:`Adding_your_own_models` *).*
[ec392464]465
[6af2785]466Method
467^^^^^^
[ec392464]468
[6af2785]469Now *Select All Data* in the *Data Explorer*, check the *Batch Mode* radio button
470at the bottom of that panel and *Send To Fitting*. A *BatchPage* will be created.
[ec392464]471
[6af2785]472.. image:: batch_button_area.bmp
[ec392464]473
[6af2785]474*NB: The Batch Page can also be created by checking the Batch Mode radio button*
475*and selecting New Fit Page under Fitting in the menu bar.*
[ec392464]476
[6af2785]477Using the drop-down menus in the *BatchPage*, now set up the *same* data set
478with the *same* model that you just fitted in single fit mode. A quick way to
479set the model parameter values is to just copy them from the earlier Single
480Fit. To do this, go back to the Single Fit *FitPage*, select *Copy Params*
481under *Edit* in the menu bar, then go back to the *BatchPage* and *Paste Params*.
[ec392464]482
[6af2785]483When ready, use the *Fit* button on the *BatchPage* to perform the fitting, NOT
484the *Fit* button on the individual *FitPage*'s.
[ec392464]485
[6af2785]486Unlike in single fit mode, the results of batch fits are not returned to
487the *BatchPage*. Instead, a spreadsheet-like :ref:`Grid_Window` will appear.
[ec392464]488
[6af2785]489If you want to visually check a graph of a particular fit, click on the name of
490a *Data set* in the *Grid Window* and then click the *View Fits* button. The
491data and the model fit will be displayed. If you select mutliple data sets they
492will all appear on one graph.
[ec392464]493
[6af2785]494.. image:: view_button.bmp
[ec392464]495
[6af2785]496*NB: In theory, returning to the BatchPage and changing the name of the I(Q)*
497*data source should also work, but at the moment whilst this does change the*
498*data set displayed it always superimposes the 'theory' corresponding to the*
499*starting parameters.*
[ec392464]500
[6af2785]501If you select a 'Chi2' value and click the *View Fits* button a graph of the
502residuals for that data set is displayed. Again, if you select multiple 'Chi2'
[f9250dc]503values then all the residuals data will appear on one graph. Also see
504:ref:`Assessing_Fit_Quality`.
[ec392464]505
[6af2785]506Chain Fitting
507^^^^^^^^^^^^^
[ec392464]508
[6af2785]509By default, the *same* parameter values copied from the initial single fit into
510the *BatchPage* will be used as the starting parameters for all batch fits. It
511is, however, possible to get *SasView* to use the results of a fit to a preceding
512data set as the starting parameters for the next fit in the sequence. This
513variation of batch fitting is called *Chain Fitting*, and will considerably speed
514up model-fitting if you have lots of very similar data sets where a few parameters
515are gradually changing. Do not use chain fitting on disparate data sets.
[ec392464]516
[6af2785]517To use chain fitting, select *Chain Fitting* under *Fitting* in the menu bar. It
518toggles on/off, so selecting it again will switch back to normal batch fitting.
[ec392464]519
[6af2785]520.. _Grid_Window:
[ec392464]521
[6af2785]522Grid Window
523^^^^^^^^^^^
[ec392464]524
[6af2785]525The *Grid Window* provides an easy way to view the results from batch fitting.
526It will be displayed automatically when a batch fit completes, but may be
527opened at any time by selecting *Show Grid Window* under *View* in the menu
528bar.
[ec392464]529
[6af2785]530.. image:: restore_batch_window.bmp
[ec392464]531
[6af2785]532Once a batch fit is completed, all model parameters are displayed but *not*
533their uncertainties. To view the uncertainties, click on a given column then
534go to *Edit* in the menu bar, select *Insert Column Before* and choose the
535required data from the list. An empty column can be inserted in the same way.
[ec392464]536
[6af2785]537To remove a column from the grid, click on the column header and choose
538*Remove Column* under *Edit* in the menu bar. The same functionality also
539allows you to re-order columns.
[ec392464]540
[6af2785]541*NB: You cannot insert/remove/re-order the rows in the Grid Window.*
[ec392464]542
[6af2785]543All of the above functions are also available by right-clicking on a column
544label.
[ec392464]545
[6af2785]546.. image:: edit_menu.bmp
[ec392464]547
[6af2785]548*NB: If there is an existing Grid Window and another batch fit is performed,*
549*an additional 'Table' tab will be added to the Grid Window.*
[ec392464]550
[6af2785]551The parameter values in the *currently selected* table of the *Grid Window*
552can be output to a CSV file by choosing *Save As* under *File* in the (*Grid*
553*Window*) menu bar. The default filename includes the date and time that the
554batch fit was performed.
[ec392464]555
[6af2785]556Saved CSV files can be reloaded by choosing *Open* under *File* in the *Grid*
557*Window* menu bar. The loaded parameters will appear in a new table tab.
[ec392464]558
[6af2785]559.. image:: file_menu.bmp
[ec392464]560
[6af2785]561*NB: Saving the Grid Window does not save any experimental data, residuals*
562*or actual model fits. Consequently if you reload a saved CSV file the*
563*ability to View Fits will be lost.*
[ec392464]564
[6af2785]565Parameter Plots
566^^^^^^^^^^^^^^^
[ec392464]567
[6af2785]568Any column of *numeric* parameter values can be plotted against another using
569the *Grid Window*. Simply select one column at the time and click the *Add*
570button next to the required *X/Y-axis Selection Range* text box. When both
571the X and Y axis boxes have been completed, click the *Plot* button.
[ec392464]572
[6af2785]573When the *Add* button is clicked, *SasView* also automatically completes the
574*X/Y-axis Label* text box with the heading from Row 1 of the selected table,
575but different labels and units can be entered manually.
[ec392464]576
577.. image:: plot_button.bmp
578
[6af2785]579The *X/Y-axis Selection Range* can be edited manually. The text control box
580recognises the operators +, -, \*, /, or 'pow', and allows the following
581types of expression :
582 
583  1) if an axis label range is a function of 1 or more *columns*, write
584     this type of expression
[ec392464]585
[6af2785]586     constant1 * column_name1 [minimum row index :  maximum  row index]
587     operator constant2 * column_name2 [minimum row index :  maximum  row index]
[ec392464]588
[6af2785]589     Example: radius [2 : 5] -3 * scale [2 : 5]
[ec392464]590
[6af2785]591  2) if only some *values* of a given column are needed but the range between
592     the first row and the last row used is not continuous, write this type of
593     expression
[ec392464]594
[6af2785]595     column_name1 [minimum row index1 :  maximum  row index1] , column_name1
596     [minimum row index2 :  maximum  row index2]
[ec392464]597
[6af2785]598     Example: radius [2 : 5] , radius [10 : 25]
[ec392464]599
600.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
[6af2785]601
602.. note::  This help document was last changed by Steve King, 04Jun2015
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