Merge pull request #365 from JuliaOpt/conv

Fix `conv` docs; add test of the definition

Author: ericphanson

docs/src/operations.md

@@ -56,7 +56,7 @@ LP solver.
 | `tr(x)`                                          | $\mathrm{tr} \left(X \right)$                                                                                                                  | affine  | increasing                                                                                                | none                           |
 | `partialtrace(x,sys,dims)`                       | Partial trace                                                                                                                                         | affine  | increasing                                                                                                | none                           |
 | `partialtranspose(x,sys,dims)`                   | Partial transpose                                                                                                                                     | affine  | increasing                                                                                                | none                           |
-| `conv(h,x)`                                      | $h \in \mathbb{R}^m$ $x \in \mathbb{R}^m$ $h\star x \in \mathbb{R}^{m+n-1}$ entry $i$ is given by $\sum_{j=1}^m h_jx_{i-j}$ | affine  | increasing if $h\ge 0$ decreasing if $h\le 0$ not monotonic otherwise                           | PR: $h$ is constant        |
+| `conv(h,x)`                                      | $h \in \mathbb{R}^m$, $x \in \mathbb{R}^n$, $h\star x \in \mathbb{R}^{m+n-1}$; entry $i$ is given by $\sum_{j=1}^m h_jx_{i-j+1}$ with $x_k=0$ for $k$ out of bounds | affine  | increasing if $h\ge 0$ decreasing if $h\le 0$ not monotonic otherwise                           | PR: $h$ is constant        |
 | `min(x,y)`                                       | $\min(x,y)$                                                                                                                                      | concave | increasing                                                                                                | none                           |
 | `max(x,y)`                                       | $\max(x,y)$                                                                                                                                      | convex  | increasing                                                                                                | none                           |
 | `pos(x)`                                         | $\max(x,0)$                                                                                                                                      | convex  | increasing                                                                                                | none                           |

test/definitions.jl

@@ -0,0 +1,16 @@
+function _conv(h, x)
+    m = length(h)
+    n = length(x)
+    zero_pad_x(i) = 1 <= i <= n ? x[i] : 0
+    [ sum(h[j]*zero_pad_x(i-j+1) for j = 1:m) for i = 1:m+n-1  ]
+end
+
+@testset "Conv (issue #364)" begin
+    n = 3
+    m = 11
+    h = rand(m)
+    x = rand(n)
+    hvar = Variable(m)
+    hvar.value = h
+    @test evaluate(conv(hvar, x)) ≈ _conv(h, x)
+end

test/runtests.jl

@@ -26,6 +26,10 @@ Random.seed!(2)
     end
 end
 
+@testset "Definitions" begin
+    include("definitions.jl")
+end
+
 @testset "Convex" begin
     include("test_utilities.jl")
     include("deprecations.jl")