cosine is done

hugo/content/ref/sample/particle/ff/ripples/cosine.md

@@ -5,7 +5,7 @@ weight = 20
 
 ## Cosine ripple
 
-A ripple with an asymmetric saw-tooth profile that is uniform in $x$-direction.
+A ripple with a symmetric cosine profile that is uniform in $x$-direction.
 
 <img src="/img/draw/ff/3d/CosineRipple.png" width="30%" >
 <img src="/img/draw/ff/2d/CosineRipple_xy.svg" width="30%">
@@ -14,18 +14,15 @@ A ripple with an asymmetric saw-tooth profile that is uniform in $x$-direction.
 #### Constructor
 
 ```python
-SawtoothRippleBox(L, W, H, d)
+CosineRippleBox(L, W, H)
+CosineRippleGauss(L, W, H)
+CosineRippleLorentz(L, W, H)
 ```
 
 Parameters:
 - L, length
 - W, width
 - H, height
-- d, asymmetry
-
-Constraint:
-
-$ |d| \le W/2 $
 
 #### Usage
 
@@ -33,74 +30,28 @@ As for any other [Form factor](/ref/sample/particle/ff).
 
 #### Implementation
 
-Class {{% ref-class "Sample/HardParticle" "SawtoothRipple" %}} inherits from the interface class
+Class {{% ref-class "Sample/HardParticle" "CosineRipple" %}} inherits from the interface class
 {{% ref-class "Sample/Particle" "IFormFactor" %}}.
 
-
 Form factor is computed as
 
-$$  F(\mathbf{q}) = f_\parallel(q_x)
-  i\text{e}^{-i q_y d}
-  \left[
-    \text{e}^{i \alpha_{-}/2} \text{sinc}\left( \frac{\alpha_{+}}{2} \right)
-    - \text{e}^{i \alpha_{+}/2} \text{sinc}\left( \frac{\alpha_{-}}{2} \right)
-  \right], $$
-
-with the notation
-$$  \alpha_{+} = H q_z + \frac{q_y W}{2} + q_y d, \quad
-  \alpha_{-} = H q_z - \frac{q_y W}{2} + q_y d. $$
-
-The longitudinal factor $ f_\parallel $ is defined according to "box shape" in $XZ$ plane:
-
-$$ f_\parallel(q_x)=L \space \text{sinc}(q_xL/2). $$
+$$  F(\mathbf{q}) = f_\parallel(q_x) f_\bot(q_y,q_z), $$
 
+where $ f_\bot(q_y,q_z) $ is computed numerically
+and $ f_\parallel(q_x) $ is chosen according to [longitudinal profile](/ref/sample/particle/ff/ripples/).
 
 Volume [has been validated]({{% url-src %}}/Tests/Unit/Sample/FormFactorBasicTest.cpp)
 against
 $$ V=\dfrac{LWH}{2}. $$
 
-#### Other shapes
-
-We have already stated that transversal $YZ$ and longitudinal $XZ$ profiles are set separately.
-For other longitudinal shapes use
-
-```python
-SawtoothRippleGauss(L, W, H, d)
-SawtoothRippleLorentz(L, W, H, d)
-```
-
-with the corresponding factor $ f_\parallel(q_x) $ inside.
-
-Other transversal profiles are also available:
-
-cosine profile
-```python
-CosineRippleBox(L, W, H)
-CosineRippleGauss(L, W, H)
-CosineRippleLorentz(L, W, H)
-```
-
-and rectangular profile
-
-```python
-Box(L, W, H)
-BarGauss(L, W, H)
-BarLorentz(L, W, H)
-```
-
-
 #### Scattering
 
-Scattering by uncorrelated, oriented sawtooth ripples for horizontal incidence. Rotation around $z$ axis:
+Scattering by uncorrelated, oriented cosine ripples for horizontal incidence. Rotation around $z$ axis:
 
-<img src="/img/auto/ff/SawtoothRippleBox.png">
+<img src="/img/auto/ff/CosineRippleBox.png">
 
-Generated by {{% ref-ex "ff/SawtoothRippleBox.py" %}}.
+Generated by {{% ref-ex "ff/CosineRippleBox.py" %}}.
 
 #### History
 
-"CosineRippleBox" and "SawtoothRippleBox" replicate "Ripple1" and "Ripple2" from FitGISAXS [[Babonneau 2013](/lit/babonneau2013)].
-
-Full documentation and API support for all ripple form factors appeared in
-BornAgain 1.17. Before that release, the Lorentz factor $ f_\parallel $ had an extra factor of 2.5.
-The Gauss factor  $ f_\parallel $ was completely wrong up through BornAgain 20.
+"CosineRippleBox" replicates "Ripple1" from FitGISAXS [[Babonneau 2013](/lit/babonneau2013)].