Fix #701

Author: dlfivefifty

Project.toml

@@ -1,6 +1,6 @@
 name = "ApproxFun"
 uuid = "28f2ccd6-bb30-5033-b560-165f7b14dc2f"
-version = "0.11.12"
+version = "0.11.13"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"

src/Extras/autodifferentiation.jl

@@ -12,8 +12,9 @@ domain(df::DualFun) = domain(df.f)
 differentiate(d::DualFun) = DualFun(d.f',Derivative(rangespace(d.J))*d.J)
 integrate(d::DualFun) = DualFun(integrate(d.f),Integral(rangespace(d.J))*d.J)
 function cumsum(d::DualFun)
-    Q=Integral(rangespace(d.J))*d.J
-    DualFun(cumsum(d.f),(I-Evaluation(rangespace(Q),leftendpoint))*Q)
+    Q = Integral(rangespace(d.J))*d.J
+    rs = rangespace(Q)
+    DualFun(cumsum(d.f),Q-ones(rs)*Evaluation(rs,leftendpoint)*Q)
 end
 
 # total definite integral of a function

test/ExtrasTest.jl

@@ -1,5 +1,5 @@
 using ApproxFun, Test, DualNumbers
-    import ApproxFun: eigs
+import ApproxFun: eigs
 
 @testset "Extras" begin
     @testset "Dual numbers" begin
@@ -123,6 +123,10 @@ using ApproxFun, Test, DualNumbers
         u = 0.5*one(x)
         u = newton(N_single, [u])
         @test norm(u - u1) < 1e-15
+    end
 
+    @testset "cumsum (#701)" begin
+        d = ApproxFun.DualFun(Fun())
+        @test cumsum(d).J*Fun() ≈ Fun(x -> (x^2-1)/2)
     end
 end