Implemented some form of LM optimization, but it's proper fucked somehow.

lib/Petzval/Optics.hs

@@ -28,6 +28,8 @@ class Material mat where
   iorAtWavelength :: Double -> mat -> Double
   -- | A material with a constant IOR of 1
   air :: mat
+  air = constMat 1
+  constMat :: Double -> mat
   
 -- | Calculates IOR based on the Sellemeier equation
 data SellemeierMat = SellemeierMat [(Double, Double)]
@@ -37,6 +39,7 @@ instance Material SellemeierMat where
     where contrib (b,c) = b * w2 / (w2 - c)
           w2 = λ ^ 2
   air = SellemeierMat []
+  constMat ior = SellemeierMat [(ior * ior - 1, 0)]
 
 -- | A material with a constant IOR
 newtype ConstMat = ConstMat Double
@@ -45,6 +48,7 @@ newtype ConstMat = ConstMat Double
 instance Material ConstMat where
   iorAtWavelength _ (ConstMat ior) = ior
   air = ConstMat 1
+  constMat = ConstMat
 
 -- | A representation of IOR as (previous,new) IOR at a surface
 data BakedIOR = BakedIOR Double Double
@@ -74,30 +78,7 @@ isStop _ = False
 isSurface :: Element mat a -> Bool
 isSurface Surface{} = True
 isSurface _ = False
-    {-
--- | The space after the current element
-thickness :: Lens (Element mat a) (Element mat a) a a
-thickness inj (s@Surface{_thickness}) = (\nt -> s{_thickness=nt}) <$> inj _thickness
-thickness inj (s@Stop{_thickness}) = (\nt -> s{_thickness=nt}) <$> inj _thickness
--- | The outside radius of the element. Rays that intersect the element beyond this radius are considered to have missed.
-outsideRadius :: Lens (Element mat a) (Element mat a) a a
-outsideRadius inj (s@Surface{_outsideRadius}) = (\nt -> s{_outsideRadius=nt}) <$> inj _outsideRadius
-outsideRadius inj (s@Stop{_outsideRadius}) = (\nt -> s{_outsideRadius=nt}) <$> inj _outsideRadius
 
-infinity :: (RealFloat a) => a
-infinity = encodeFloat (floatRadix 0 - 1) (snd $ floatRange 0)
--- | The radius of curvature of an element. This is 1 for stops
-roc :: RealFloat a => Lens (Element mat a) (Element mat a) a a
-roc inj (s@Surface{_roc}) = (\nt -> s{_roc=nt}) <$> inj _roc
-roc inj (s@Stop{}) = (const s) <$> inj infinity
-
--- | The material that a surface transitions into
---
--- For stops, this returns None and ignores being set.
-material :: (Material mat, Material mat') => Lens (Element mat a) (Element mat' a) (Maybe mat) (Maybe mat')
-material inj (s@Surface{_thickness, _outsideRadius, _roc, _material}) = (\nt -> Surface{_material=fromMaybe air nt, _thickness, _outsideRadius, _roc}) <$> inj (Just _material)
-material inj (s@Stop{_thickness, _outsideRadius}) = (const Stop{_thickness, _outsideRadius}) <$> inj Nothing
--}
 -- | Translate a lens element from one FP type to another. E.g., can be used to convert from scalars to the types in an automatic differentiation tool.
 liftFp :: (Applicative f) => (fp -> f fp') -> Element m fp -> f (Element m fp')
 liftFp inj (s@Stop{_thickness, _outsideRadius}) = Stop <$> inj _thickness <*> inj _outsideRadius