Changes in / [094e320:c515b1b] in sasmodels

Files:

• TESTS.txt (added)
• sasmodels/models/poly_gauss_coil.py (modified) (3 diffs)

sasmodels/models/poly_gauss_coil.py

@@ -50 +50 @@
 """
 
-from numpy import inf, sqrt, power
+from numpy import inf, sqrt, exp, power
 
 name =  "poly_gauss_coil"
@@ -69 +69 @@
 def Iq(q, i_zero, radius_gyration, polydispersity):
     # pylint: disable = missing-docstring
-    # need to trap the case of the polydispersity being 1 (ie, monodispersity)
     u = polydispersity - 1.0
-    if polydispersity == 1:
-       minusoneonu = -1.0 / u
-    else:
-       minusoneonu = -1.0 / u
     z = ((q * radius_gyration) * (q * radius_gyration)) / (1.0 + 2.0 * u)
     if (q == 0).any():
-       inten = i_zero
+        inten = i_zero
     else:
-       inten = i_zero * 2.0 * (power((1.0 + u * z),minusoneonu) + z - 1.0 ) / ((1.0 + u) * (z * z))
+    # need to trap the case of the polydispersity being 1 (ie, monodispersity!)
+        if polydispersity == 1:
+            inten = i_zero * 2.0 * (exp(-z) + z - 1.0 ) / (z * z)
+        else:
+            minusoneonu = -1.0 / u
+            inten = i_zero * 2.0 * (power((1.0 + u * z),minusoneonu) + z - 1.0 ) / ((1.0 + u) * (z * z))
     return inten
-Iq.vectorized =  True  # Iq accepts an array of q values
+#Iq.vectorized =  True  # Iq accepts an array of q values
 
 def Iqxy(qx, qy, *args):
@@ -100 +100 @@
                background = 'background')
 
+# these unit test values taken from SasView 3.1.2
 tests =  [
-    [{'scale': 70.0, 'radius_gyration': 75.0, 'polydispersity': 2.0, 'background': 0.0},
+    [{'scale': 1.0, 'i_zero': 70.0, 'radius_gyration': 75.0, 'polydispersity': 2.0, 'background': 0.0},
      [0.0106939, 0.469418], [57.6405, 0.169016]],
     ]