Changeset a309667 in sasview for src/sas/sascalc

Timestamp:

Sep 11, 2017 6:07:53 AM (7 years ago)

Author:

lewis

Branches:

master, ESS_GUI, ESS_GUI_Docs, ESS_GUI_batch_fitting, ESS_GUI_bumps_abstraction, ESS_GUI_iss1116, ESS_GUI_iss879, ESS_GUI_iss959, ESS_GUI_opencl, ESS_GUI_ordering, ESS_GUI_sync_sascalc, magnetic_scatt, release-4.2.2, ticket-1009, ticket-1094-headless, ticket-1242-2d-resolution, ticket-1243, ticket-1249, ticket885, unittest-saveload

Children:

ccf58fb

Parents:

9b90bf8

Message:

Tidy up IDF code

File:

• src/sas/sascalc/corfunc/transform_thread.py (modified) (1 diff)

src/sas/sascalc/corfunc/transform_thread.py

@@ -53 +53 @@
 
             # ----- Interface Distribution function -----
-            # dmax = 200.0 # Max real space value to calculate IDF up to
-            # dstep = 0.5 # Evaluate the IDF in steps of dstep along the real axis
-            # qmax = 1.0 # Max q value to integrate up to when calculating IDF
+            idf = dct(-qs**4 * (iqs-background))
 
-            # Units of x axis depend on qmax (for some reason?). This scales
-            # the xgamma array appropriately, since qmax was set to 0.6 in
-            # the original fortran code.
-            # x_scale = qmax / 0.6
+            if self.check_if_cancelled(): return
 
-            # xgamma = np.arange(0, dmax/x_scale, step=dstep/x_scale)
-            # idf = np.zeros(len(xgamma))
-            idf = dct(-qs**4 * (iqs-background))
+            # Manually calculate IDF(0.0), since scipy DCT tends to give us a
+            # very large negative value.
+            # IDF(x) = int_0^inf q^4 * I(q) * cos(q*x) * dq
+            # => IDF(0) = int_0^inf q^4 * I(q) * dq
             idf[0] = trapz(-qs**4 * (iqs-background), qs)
-            idf /= Q
-
-            # nth moment = integral(q^n * I(q), q=0, q=inf)
-            # moment = np.zeros(5)
-            # for n in range(5):
-            #     integrand = qs**n * (iqs-background)
-            #     moment[n] = trapz(integrand[qs < qmax], qs[qs < qmax])
-            #     if self.check_if_cancelled(): return
-            #
-            # # idf(x) = -integral(q^4 * I(q)*cos(qx), q=0, q=inf) / 2nd moment
-            # # => idf(0) = -integral(q^4 * I(q), 0, inf) / (2nd moment)
-            # #  = -(4th moment)/(2nd moment)
-            # idf[0] = -moment[4] / moment[2]
-            # for i in range(1, len(xgamma)):
-            #     d = xgamma[i]
-            #
-            #     integrand = -qs**4 * (iqs-background) * np.cos(d*qs)
-            #     idf[i] = trapz(integrand[qs < qmax], qs[qs < qmax])
-            #     idf[i] /= moment[2]
-            #     if self.check_if_cancelled(): return
-            #
-            # xgamma *= x_scale
+            idf /= Q # Normalise using scattering invariant
 
         except Exception as e: