--- a/grid.jl	Thu Jan 10 10:15:27 2019 +0100
+++ b/grid.jl	Thu Jan 10 10:38:42 2019 +0100
@@ -4,54 +4,108 @@
 abstract type Grid end
 
 function numberOfDimensions(grid::Grid)
-    error("Not yet implemented")
+    error("Not implemented for abstact type Grid")
 end
 
 function numberOfPoints(grid::Grid)
-    error("Not yet implemented")
+    error("Not implemented for abstact type Grid")
 end
 
 function points(grid::Grid)
-    error("Not yet implemented")
+    error("Not implemented for abstact type Grid")
 end
 
+# TODO: Should this be here?
 abstract type BoundaryId end
 
-# Move to seperate file.
+# EquidistantGrid is a grid with equidisant grid spacing per coordinat
+# direction. The domain is defined through the two points P1 = x̄₁, P2 = x̄₂
+# by the exterior product of the vectors obtained by projecting (x̄₂-x̄₁) onto
+# the coordinate directions. E.g for a 2D grid with x̄₁=(-1,0) and x̄₂=(1,2)
+# the domain is defined as (-1,1)x(0,2).
 struct EquidistantGrid <: Grid
-    nPointsPerDim::Vector{Int}
-    limits::Vector{Pair{Real, Real}}
-    function EquidistantGrid(nPointsPerDim, lims)
-        @assert length(lims) == length(nPointsPerDim)
+    numberOfPointsPerDim::Tuple # First coordinate direction stored first, then
+                                # second, then third.
+    limits::NTuple{2,Tuple} # Stores the two points which defines the range of
+                            # the e.g (-1,0) and (1,2) for a domain of size
+                            # (-1,1)x(0,2)
+
+    # General constructor
+    function EquidistantGrid(nPointsPerDim::Tuple, lims::NTuple{2,Tuple})
+        @assert length(nPointsPerDim) > 0
+        @assert count(x -> x > 0, nPointsPerDim) == length(nPointsPerDim)
+        @assert length(lims[1]) == length(nPointsPerDim)
+        @assert length(lims[2]) == length(nPointsPerDim)
+        # TODO: Assert that the same values are not passed in both lims[1] and lims[2]
+        #       i.e the domain length is positive for all dimensions
         return new(nPointsPerDim, lims)
     end
+    # 1D constructor which can be called as EquidistantGrid(m, (xl,xr))
+    function EquidistantGrid(nPointsPerDim::Integer, lims::NTuple{2,Integer})
+        return EquidistantGrid((nPointsPerDim,), ((lims[1],),(lims[2],)))
+    end
+
 end
 
+# Returns the number of dimensions of an EquidistantGrid.
+#
+# @Input: grid - an EquidistantGrid
+# @Return: numberOfPoints - The number of dimensions
 function numberOfDimensions(grid::EquidistantGrid)
-    return length(grid.nPointsPerDim)
+    return length(grid.numberOfPointsPerDim)
 end
 
+# Computes the total number of points of an EquidistantGrid.
+#
+# @Input: grid - an EquidistantGrid
+# @Return: numberOfPoints - The total number of points
 function numberOfPoints(grid::EquidistantGrid)
-    numberOfPoints = grid.nPointsPerDim[1];
-    for i = 2:length(grid.nPointsPerDim);
-        numberOfPoints = numberOfPoints*grid.nPointsPerDim[i]
+    numberOfPoints = grid.numberOfPointsPerDim[1];
+    for i = 2:length(grid.numberOfPointsPerDim);
+        numberOfPoints = numberOfPoints*grid.numberOfPointsPerDim[i]
     end
     return numberOfPoints
 end
 
+# Computes the grid spacing of an EquidistantGrid, i.e the unsigned distance
+# between two points for each coordinate direction.
+#
+# @Input: grid - an EquidistantGrid
+# @Return: h̄ - Grid spacing for each coordinate direction stored in a tuple.
+function spacings(grid::EquidistantGrid)
+    h̄ = Vector{Real}(undef, numberOfDimensions(grid))
+    for i ∈ eachindex(h̄)
+        h̄[i] = abs(grid.limits[2][i]-grid.limits[1][i])/(grid.numberOfPointsPerDim[i]-1)
+    end
+    return Tuple(h̄)
+end
+
+# Computes the points of an EquidistantGrid as a vector of tuples. The vector is ordered
+# such that points in the first coordinate direction varies first, then the second
+# and lastely the third (if applicable)
+#
+# @Input: grid - an EquidistantGrid
+# @Return: points - the points of the grid.
 function points(grid::EquidistantGrid)
-    points = Vector{Real}(undef, numberOfPoints(grid))
-    for i = 1:numberOfDimensions(grid)
-        lims = limitsForDimension(grid,i)
-        points = range(lims.first, stop=lims.second, length=grid.nPointsPerDim[i])
+    # Compute signed grid spacings
+    dx̄ = Vector{Real}(undef, numberOfDimensions(grid))
+    for i ∈ eachindex(dx̄)
+        dx̄[i] = (grid.limits[2][i]-grid.limits[1][i])/(grid.numberOfPointsPerDim[i]-1)
+    end
+    dx̄ = Tuple(dx̄)
+
+    nPoints = numberOfPoints(grid)
+    points = Vector{NTuple{numberOfDimensions(grid),Real}}(undef, nPoints)
+    # Compute the points based on their Cartesian indices and the signed
+    # grid spacings
+    cartesianIndices = CartesianIndices(grid.numberOfPointsPerDim)
+    for i ∈ 1:nPoints
+        ci = Tuple(cartesianIndices[i]) .-1
+        points[i] = grid.limits[1] .+ dx̄.*ci
     end
     return points
 end
 
-function limitsForDimension(grid::EquidistantGrid, dim::Int)
-    return grid.limits[dim]
-end
-
 function plotOnGrid(grid::EquidistantGrid,v::Vector)
     dim = numberOfDimensions(grid)
     x = points(grid)