Changeset 525f3a9 in sasmodels

Timestamp:

Nov 20, 2015 5:58:44 AM (9 years ago)

Author:

smk78

Branches:

master, core_shell_microgels, costrafo411, magnetic_model, release_v0.94, release_v0.95, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests

Children:

29fc2a3

Parents:

5d80bbf

Message:

Scale & Background removed from model calculation as implicit parameters
in sasmodels models; parameter 'm' changed to 'power'; re-parameterized
with just q and 'power'.

File:

• sasmodels/models/power_law.py (modified) (3 diffs)

sasmodels/models/power_law.py

@@ -10 +10 @@
 .. math::
 
-    I(q) = \text{scale} \cdot q^{-m} + \text{background}
+    I(q) = \text{scale} \cdot q^{-power} + \text{background}
 
-Note the minus sign in front of the exponent. The exponent *m* 
-should therefore be entered as a **positive** number.
+Note the minus sign in front of the exponent. The exponent *power* 
+should therefore be entered as a **positive** number for fitting.
 
 Also note that unlike many other models, *scale* in this model 
@@ -35 +35 @@
 description = """\
         Evaluates the function
-        I(q) = scale * q^(-m) + bkgd
-        NB: enter m as a positive number!
+        I(q) = scale * q^(-power) + background
+        NB: enter power as a positive number!
         """
 category = "shape-independent"
 
 #             ["name", "units", default, [lower, upper], "type", "description"],
-parameters = [["scale", "", 1.0, [-inf, inf], "", "Power law scale factor"],
-              ["m", "", 4.0, [-inf, inf], "", "Power law exponent"],
-              ["bkgd", "", 0.0, [-inf, inf], "", "Background level"]]
+parameters = [["power", "", 4.0, [-inf, inf], "", "Power law exponent"]]
 
-def Iq(scale,m,bkgd):
-    inten = (scale * q ** m + bkgd)
+# NB: Scale and Background are implicit parameters on every model
+def Iq(q,power):
+    inten = (q**-power)
     return inten
 Iq.vectorized = True  # Iq accepts an array of Q values
@@ -55 +54 @@
 
 demo = dict(scale=1.0,
-            m=4.0,
-            bkgd=0.0)
+            power=4.0,
+            background=0.0)
 
 oldname = "PowerLawAbsModel"
 oldpars = dict(scale='scale',
-               m='m',
-               bkgd='background')
+               power='m',
+               background='background')
 
 tests = [
-        [ {'scale': 1.0, 'm': 4.0, 'bkgd' : 0.0}, [0.0106939, 0.469418], [7.64644e+07, 20.5949]]
+        [ {'scale': 1.0, 'power': 4.0, 'background' : 0.0}, [0.0106939, 0.469418], [7.64644e+07, 20.5949]]
         ]