Implement sum (#44)

* Add sum for ContinuousPolynomial

* sum for PiecewisePolynomial

* Update continuouspolynomial.jl

Author: dlfivefifty

Project.toml

@@ -1,7 +1,7 @@
 name = "PiecewiseOrthogonalPolynomials"
 uuid = "4461d12d-4663-4550-8580-cb764c85e20f"
 authors = ["Sheehan Olver <[email protected]>"]
-version = "0.2.1"
+version = "0.2.2"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"

src/continuouspolynomial.jl

@@ -46,6 +46,7 @@ factorize(V::SubQuasiArray{T,N,<:ContinuousPolynomial{0},<:Tuple{Inclusion,Block
     factorize(view(PiecewisePolynomial(parent(V)), parentindices(V)...), dims...)
 
 plan_grid_transform(P::ContinuousPolynomial{0}, args...) = plan_grid_transform(PiecewisePolynomial(P), args...)
+plan_grid_transform(P::ContinuousPolynomial{0}, lng::Union{Integer, Block{1}}, args...) = plan_grid_transform(PiecewisePolynomial(P), lng, args...)
 
 for grd in (:grid, :plotgrid)
     @eval $grd(C::ContinuousPolynomial, n...) = $grd(PiecewisePolynomial(C), n...)
@@ -203,4 +204,15 @@ end
 
 singularities(C::ContinuousPolynomial{λ}) where λ = C
 basis_singularities(C::ContinuousPolynomial) = C
-singularitiesbroadcast(_, C::ContinuousPolynomial) = C # Assume we stay smooth
+singularitiesbroadcast(_, C::ContinuousPolynomial) = C # Assume we stay smooth
+
+
+###
+# sum
+###
+
+_sum(C::ContinuousPolynomial{0}, dims) = _sum(PiecewisePolynomial(C), dims)
+function _sum(C::ContinuousPolynomial, dims)
+    P = ContinuousPolynomial{0}(C)
+    _sum(P, dims) * (P \ C)
+end

src/piecewisepolynomial.jl

@@ -119,4 +119,9 @@ end
 
 singularities(C::PiecewisePolynomial) = C
 basis_singularities(C::PiecewisePolynomial) = C
-singularitiesbroadcast(_, C::PiecewisePolynomial) = C # Assume we stay piecewise smooth
+singularitiesbroadcast(_, C::PiecewisePolynomial) = C # Assume we stay piecewise smooth
+
+####
+# sum
+####
+_sum(P::PiecewisePolynomial, dims) = blockvec(diff(P.points)/2 .* sum(P.basis; dims=1))'

test/test_continuouspolynomial.jl

@@ -150,4 +150,11 @@ using PiecewiseOrthogonalPolynomials, StaticArrays, InfiniteArrays, ContinuumArr
         f = expand(C, exp)
         @test expand(exp.(f))[0.1] ≈ exp(exp(0.1))
     end
+
+    @testset "sum" begin
+        r = [-1, 0.1, 0.2, 1]
+        P = ContinuousPolynomial{0}(r)
+        C = ContinuousPolynomial{1}(r)
+        @test sum(expand(P, exp)) ≈ sum(expand(C, exp)) ≈ ℯ - 1/ℯ
+    end
 end