Changeset 0d87e79 in sasmodels

Timestamp:

Aug 6, 2018 9:23:15 AM (6 years ago)

Author:

GitHub <noreply@…>

Branches:

master, core_shell_microgels, magnetic_model, ticket-1257-vesicle-product, ticket_1156, ticket_1265_superball, ticket_822_more_unit_tests

Children:

c11d09f

Parents:

1711569 (diff), 9e7837a (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 Butler <butlerpd@…> (08/06/18 09:23:15)

git-committer:

GitHub <noreply@…> (08/06/18 09:23:15)

Message:

Merge pull request #74 from SasView?/ticket-1104-resolution

Ticket 1102: use asymmetric integration window for resolution, (-2.5,+3.0) sigma

This looks clearly better than the “log basis” currently implemented. However we will want to revisit this. Further notes added to ticket #1102. Merging this for 4.2.0

addresses #1102.

Location:

sasmodels

Files:

• resolution.py (modified) (5 diffs)
• modelinfo.py (modified) (1 diff)

sasmodels/resolution.py

@@ -20 +20 @@
 MINIMUM_RESOLUTION = 1e-8
 MINIMUM_ABSOLUTE_Q = 0.02  # relative to the minimum q in the data
-PINHOLE_N_SIGMA = 2.5 # From: Barker & Pedersen 1995 JAC
+# According to (Barker & Pedersen 1995 JAC), 2.5 sigma is a good limit.
+# According to simulations with github.com:scattering/sansresolution.git
+# it is better to use asymmetric bounds (2.5, 3.0)
+PINHOLE_N_SIGMA = (2.5, 3.0)
 
 class Resolution(object):
@@ -90 +93 @@
         # from the geometry, they may appear since we are using a truncated
         # gaussian to represent resolution rather than a skew distribution.
-        cutoff = MINIMUM_ABSOLUTE_Q*np.min(self.q)
-        self.q_calc = self.q_calc[self.q_calc >= cutoff]
+        #cutoff = MINIMUM_ABSOLUTE_Q*np.min(self.q)
+        #self.q_calc = self.q_calc[self.q_calc >= cutoff]
 
         # Build weight matrix from calculated q values
@@ -188 +191 @@
     cdf = erf((edges[:, None] - q[None, :]) / (sqrt(2.0)*q_width)[None, :])
     weights = cdf[1:] - cdf[:-1]
-    # Limit q range to +/- 2.5 sigma
-    qhigh = q + nsigma*q_width
-    #qlow = q - nsigma*q_width  # linear limits
-    qlow = q*q/qhigh  # log limits
+    # Limit q range to (-2.5,+3) sigma
+    try:
+        nsigma_low, nsigma_high = nsigma
+    except TypeError:
+        nsigma_low = nsigma_high = nsigma
+    qhigh = q + nsigma_high*q_width
+    qlow = q - nsigma_low*q_width  # linear limits
+    ##qlow = q*q/qhigh  # log limits
     weights[q_calc[:, None] < qlow[None, :]] = 0.
     weights[q_calc[:, None] > qhigh[None, :]] = 0.
@@ -365 +372 @@
 
 
-def pinhole_extend_q(q, q_width, nsigma=3):
+def pinhole_extend_q(q, q_width, nsigma=PINHOLE_N_SIGMA):
     """
     Given *q* and *q_width*, find a set of sampling points *q_calc* so
@@ -371 +378 @@
     function.
     """
-    q_min, q_max = np.min(q - nsigma*q_width), np.max(q + nsigma*q_width)
+    try:
+        nsigma_low, nsigma_high = nsigma
+    except TypeError:
+        nsigma_low = nsigma_high = nsigma
+    q_min, q_max = np.min(q - nsigma_low*q_width), np.max(q + nsigma_high*q_width)
     return linear_extrapolation(q, q_min, q_max)
 

sasmodels/modelinfo.py

@@ -589 +589 @@
                 Parameter('up:frac_f', '', 0., [0., 1.],
                           'magnetic', 'fraction of spin up final'),
-                Parameter('up:angle', 'degress', 0., [0., 360.],
+                Parameter('up:angle', 'degrees', 0., [0., 360.],
                           'magnetic', 'spin up angle'),
             ])