Changeset f5f8553 in sasview for src/sas/sasgui/perspectives/fitting/media/fitting_help.rst

Timestamp:

Mar 31, 2019 5:43:12 AM (5 years ago)

Author:

GitHub <noreply@…>

Parents:

6d7b252b (diff), d4cde37 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

git-author:

Paul Kienzle <pkienzle@…> (03/31/19 05:43:12)

git-committer:

GitHub <noreply@…> (03/31/19 05:43:12)

Message:

Merge d4cde3775cc19e3e8ac413babb90e5015eb330e7 into 6d7b252bf3722c053065645b1afe65424979127f

File:

• src/sas/sasgui/perspectives/fitting/media/fitting_help.rst (modified) (4 diffs)

src/sas/sasgui/perspectives/fitting/media/fitting_help.rst

@@ -42 +42 @@
 *  *Ellipsoid* - ellipsoidal shapes (oblate,prolate, core shell, etc)
 *  *Parellelepiped* - as the name implies
-*  *Sphere* - sheroidal shapes (sphere, core multishell, vesicle, etc)
+*  *Sphere* - spheroidal shapes (sphere, core multishell, vesicle, etc)
 *  *Lamellae* - lamellar shapes (lamellar, core shell lamellar, stacked
    lamellar, etc)
@@ -61 +61 @@
 on the *Description* button to the right.
 
+Product Models
+^^^^^^^^^^^^^^
+
+.. figure:: p_and_s_buttons.png
+
+S(Q) models can be combined with models in the other categories to generate
+what SasView calls "product models". See :ref:`Product_Models` for more
+information.
+
 Show 1D/2D
 ^^^^^^^^^^
@@ -119 +128 @@
 
 For a complete list of all the library models available in SasView, see
-the `Model Documentation <../../../index.html>`_ .
+the `Model Documentation <../../../sasgui/perspectives/fitting/models/index.html>`_ .
 
 It is also possible to add your own models.
@@ -338 +347 @@
 These optimisers form the *Bumps* package written by P Kienzle. For more information
 on each optimiser, see the :ref:`Fitting_Documentation`.
+
+.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
+
+Fitting Integer Parameters
+--------------------------
+
+Most of the parameters in SasView models will naturally take floating point (decimal) 
+values, but there are some parameters which can only have integer values. Examples 
+include, but are not limited to, the number of shells in a multilayer vesicle, the 
+number of beads in a pearl necklace, the number of arms of a star polymer, and so on.
+Wherever possible/recognised, the integer nature of a parameter is specified in the 
+respective model documentation and/or parameter table, so read the documentation 
+carefully!
+
+Integer parameters must be fitted with care.
+
+Start with your best possible guess for the value of the parameter. And using 
+*a priori* knowledge, fix as many of the other parameters as possible.
+ 
+The SasView optimizers treat integer parameters internally as floating point 
+numbers, but the values presented to the user are truncated or rounded, as 
+appropriate.
+
+In most instances integer parameters will probably be greater than zero. A good 
+policy in such cases is to use a constraint to enforce this.
+
+Because an integer parameter should, by definition, only move in integer steps, 
+problems may be encountered if the optimizer step size is too small. Similarly, 
+be **very careful** about applying polydispersity to integer parameters.
+
+The Levenberg-Marquardt and Quasi-Newton BFGS (and other derivative-based) 
+optimizers are probably best avoided for fitting models with integer parameters.
 
 .. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ