| 1 | Sasmodels |
|---|
| 2 | ========= |
|---|
| 3 | |
|---|
| 4 | Theory models for small angle scattering. |
|---|
| 5 | |
|---|
| 6 | The models provided are usable directly in the bumps fitting package and |
|---|
| 7 | in the sasview analysis package. If OpenCL is available, the models will |
|---|
| 8 | run much faster. If not, then precompiled versions will be included with |
|---|
| 9 | the distributed package. New models can be added if OpenCL or a C compiler |
|---|
| 10 | is available. |
|---|
| 11 | |
|---|
| 12 | Example |
|---|
| 13 | ------- |
|---|
| 14 | |
|---|
| 15 | The example directory contains a radial+tangential data set for an oriented |
|---|
| 16 | rod-like shape. |
|---|
| 17 | |
|---|
| 18 | The data is loaded by sas.dataloader from the sasview package, so sasview |
|---|
| 19 | is needed to run the example. |
|---|
| 20 | |
|---|
| 21 | To run the example, you need sasview, sasmodels and bumps. Assuming these |
|---|
| 22 | repositories are installed side by side, change to the sasmodels/example |
|---|
| 23 | directory and enter:: |
|---|
| 24 | |
|---|
| 25 | PYTHONPATH=..:../../sasview/src ../../bumps/run.py fit.py \ |
|---|
| 26 | cylinder --preview |
|---|
| 27 | |
|---|
| 28 | See bumps documentation for instructions on running the fit. With the |
|---|
| 29 | python packages installed, e.g., into a virtual environment, then the |
|---|
| 30 | python path need not be set, and the command would be:: |
|---|
| 31 | |
|---|
| 32 | bumps fit.py cylinder --preview |
|---|
| 33 | |
|---|
| 34 | The fit.py model accepts up to two arguments. The first argument is the |
|---|
| 35 | model type, which has been defined for cylinder, capped_cylinder, |
|---|
| 36 | core_shell_cylinder, ellipsoid, triaxial_ellipsoid and lamellar. The |
|---|
| 37 | second argument is view, which can be radial or tangential. To fit |
|---|
| 38 | both radial and tangential simultaneously, use the word "both". |
|---|
| 39 | |
|---|
| 40 | Notes |
|---|
| 41 | ----- |
|---|
| 42 | |
|---|
| 43 | cylinder.c + cylinder.py is the cylinder model with renamed variables and |
|---|
| 44 | sld scaled by 1e6 so the numbers are nicer. The model name is "cylinder" |
|---|
| 45 | |
|---|
| 46 | cylinder_clone.c + cylinder_clone.py is the cylinder model using the |
|---|
| 47 | same interface as the sasview, including calling the model CylinderModel, |
|---|
| 48 | so that it can be used as a drop-in replacement for the sasview cylinder |
|---|
| 49 | model. |
|---|
| 50 | |
|---|
| 51 | lamellar.py is an example of a single file model with embedded C code. |
|---|
| 52 | |
|---|
| 53 | Note: may want to rename form_volume to calc_volume and Iq/Iqxy to |
|---|
| 54 | calc_Iq/calc_Iqxy in model interface. Similarly ER/VR go to calc_ER/calc_VR. |
|---|
| 55 | |
|---|
| 56 | Note: It is possible to translate python code automatically to opencl, using |
|---|
| 57 | something like numba, clyther, shedskin or pypy, so maybe the kernel functions |
|---|
| 58 | could be implemented without any C syntax. |
|---|
| 59 | |
|---|
| 60 | Note: angular dispersion in theta is probably not calculated correctly, but |
|---|
| 61 | is left this way for compatibility with sasview. |
|---|
| 62 | |
|---|
| 63 | Magnetism hasn't been implemented yet. We may want a separate Imagnetic |
|---|
| 64 | calculator with the extra parameters and calculations. We should |
|---|
| 65 | return all desired spin states together so we can share the work of |
|---|
| 66 | computing the form factors for the different magnetic contrasts. This |
|---|
| 67 | will mean extending the data handler to support multiple cross sections |
|---|
| 68 | in the same data set. |
|---|
| 69 | |
|---|
| 70 | Need to implement an example kernel directly in python. Polydispersity |
|---|
| 71 | loops should be generated automatically as they are for the OpenCL models. |
|---|
| 72 | The kernels should be vectorized across Q. These will need vectorized |
|---|
| 73 | versions of numerical quadrature if we want to get reasonable performance. |
|---|
| 74 | |
|---|
| 75 | [](https://travis-ci.org/SasView/sasmodels) |
|---|
