some clean up and update changelog

CHANGELOG.md

@@ -317,6 +317,11 @@ more discussion).
   a given grid (based on its node coordinates), and returns the minimum and maximum vertices
   of the bounding box. ([#880][github-880])
 
+- CellValues and FacetValues can now store and map second order gradients (Hessians). The number
+  of gradients computed in CellValues/FacetValues is specified using the keyword arguments
+  `update_gradients::Bool` (default true) and `update_hessians::Bool` (default false) in the
+  constructors, i.e. `CellValues(...; update_hessians=true)`. 
+
 ### Changed
 
 - `create_sparsity_pattern` now supports cross-element dof coupling by passing kwarg

docs/src/topics/FEValues.md

@@ -65,7 +65,7 @@ Second order gradients of the shape functions are computed as
     \end{align}
     ```
 
-    Using the fact that $\frac{\mathrm{d}}{\mathrm{d}x_j} = J^{-1}_{sj}\frac{\mathrm{d}}{\mathrm{d}\xi_s}$, the first term in equation the equation above can be expressed as:
+    Using the fact that $\frac{\mathrm{d}}{\mathrm{d}x_j} = J^{-1}_{sj}\frac{\mathrm{d}}{\mathrm{d}\xi_s}$, the first term in the equation above can be expressed as:
 
     ```math
     \begin{align*} 

src/FEValues/GeometryMapping.jl

@@ -35,7 +35,7 @@ struct GeometryMapping{DiffOrder, IP, M_t, dMdξ_t, d2Mdξ2_t}
     M::M_t             # ::AbstractMatrix{<:Number}     Values of geometric shape functions
     dMdξ::dMdξ_t       # ::AbstractMatrix{<:Vec}        Gradients of geometric shape functions in ref-domain
     d2Mdξ2::d2Mdξ2_t   # ::AbstractMatrix{<:Tensor{2}}  Hessians of geometric shape functions in ref-domain
-                       # ::Nothing                      When not required
+
     function GeometryMapping(
         ip::IP, M::M_t, ::Nothing, ::Nothing
         ) where {IP <: ScalarInterpolation, M_t<:AbstractMatrix{<:Number}}

test/runtests.jl

@@ -37,7 +37,6 @@ include("test_utils.jl")
 #include("test_interpolations.jl")
 include("test_cellvalues.jl")
 include("test_facevalues.jl")
-asdf
 include("test_interfacevalues.jl")
 include("test_quadrules.jl")
 include("test_assemble.jl")