split off py/ex for examples; correct structure

hugo/content/py/ex/_index.md

++++
+title = "Examples"
+weight = 5
++++
+
+## Commented Python script examples
+
+{{% children %}}
\ No newline at end of file

hugo/content/py/sim/gisas/no-dwba-terms/index.md → hugo/content/py/ex/gisas-no-dwba-terms/index.md

@@ -9,7 +9,7 @@ This example shows scattering
 from a monolayer that contains a dilute random assembly
 of monodisperse cylindrical disks.
 
-This is the same system as in our [basic GISAS example]({{% ref-py "sim/gisas" %}})
+This is the same system as in our [basic GISAS example]({{% ref-py "ex/gisas" %}})
 except that there is no substrate.
 In consequence, there are no reflections,
 and therefore the DWBA boils down to the ordinary Born approximation.

hugo/content/py/fitting/gisas-fit2d/index.md

@@ -10,7 +10,7 @@ This example demonstrates fitting of 2D GISAS data.
 ## Faked experimental data
 
 The sample and instrument model is basically the same as
-in our [basic GISAS simulation example]({{% ref-py "sim/gisas" %}}),
+in our [basic GISAS simulation example]({{% ref-py "ex/gisas" %}}),
 except that it depends on four external parameters:
 beam intensity, detector background, radius and height of the cylindrical nanoparticles.
 
@@ -44,7 +44,7 @@ and terminates with the following result:
 ### Explanation
 
 The function `get_sample` is basically the same as
-in our [basic GISAS simulation example]({{% ref-py "sim/gisas" %}}),
+in our [basic GISAS simulation example]({{% ref-py "ex/gisas" %}}),
 except that radius and height of the cylindrical disks are now
 supplied as external parameters.
 These parameters are passed through the function argument `params`

hugo/content/py/instr/det/resolution/index.md

@@ -13,7 +13,7 @@ Here we show how to set a finite blur.
 * The incident angles are $\sigma_{\alpha\_i} = \sigma\_{\varphi\_i} = 0.1^{\circ}$.
 
 Besides this, the example is a DWBA simulation for our standard sample model,
- [Cylinders in DWBA]({{% ref-py "sim/gisas" %}})
+ [Cylinders in DWBA]({{% ref-py "ex/gisas" %}})
 
 * The sample is composed of monodisperse cylinders deposited on a substrate.
 * The cylinders are dilute, and positioned at random,

hugo/content/py/result/export/axes-in-different-units/index.md

@@ -8,7 +8,7 @@ weight = 20
 In this example we demonstrate how to plot intensity data with detector axes expressed in different units. It serves as a supporting example to the
 [Accessing simulation results]({{% ref-py "export/_index.md" %}}) tutorial.
 
-* The standard [Cylinders in DWBA]({{%ref-py "sim/gisas" %}}))
+* The standard [Cylinders in DWBA]({{%ref-py "ex/gisas" %}}))
 sample is used to setup the simulation.
 * When the simulation is completed, the `Simulation::result()` method is used to get a `SimulationResult` object.
 * Depending on an additional parameter `IDetector2D.NBINS`, `IDetector2D.DEGREES`, `IDetector2D.QYQZ`, it will be plotted with axes defined either in millimeters (default units of `RectangularDetector`), detector bins, degrees or in $Q$-space.

hugo/content/py/result/export/more.md

@@ -8,7 +8,7 @@ weight = 10
 This is an extended example for the further treatment of simulation results: accessing the results, plotting, cropping, slicing and exporting. This serves as a supporting example to the [Accessing simulation results
 ]({{% ref-py "export/_index.md" %}}) tutorial.
 
-* The standard [Cylinders in DWBA]({{%ref-py "sim/gisas" %}}) sample
+* The standard [Cylinders in DWBA]({{%ref-py "ex/gisas" %}}) sample
 is used for running the simulation.
 * The simulation results are retrieved as a `Histogram2D` object and then processed in various functions to achieve a resulting image.
 

hugo/content/py/sim/_index.md

@@ -9,7 +9,7 @@ To set up and run a BornAgain simulation, one needs to create an instance of
 a simulation class. This class contains information about the scattering
 target ("sample") and about the simulated instrument (beam or scan, detector).
 
-#### Simulation cclasses
+#### Simulation classes
 
 The following simulation classes are available:
 

hugo/content/py/sim/class/_index.md

 +++
 title = "Simulation classes"
-weight = 0
+weight = 10
 +++
 
 ## Simulation classes

hugo/content/py/sim/class/scattering/index.md

++++
+title = "Scattering"
+weight = 20
++++
+
+## Scattering simulation
+
+To set up and run a scattering simulation, use
+```python
+import bornagain as ba
+beam = ...
+sample = ...
+detector = ...
+simulation = ba.ScatteringSimulation(beam, sample, detector)
+# ... set options
+result = simulation.simulate()
+```
+
+For the constructor arguments, see sections [beam]({{% ref-py "instr/beam" %}})
+[sample]({{% ref-py "sample" %}}), and [detector](/py/instr/det).
+
+For optional settings, see [simulation options]({{% ref-py "sim/setup/options" %}}).
+
+For the return type of function `simulate()`,
+see [SimulationResult]({{% ref-py "result/simulation-result" %}}).