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