Check vector length in cross() (JuliaLang#26308)

halleysfifthinc · Mar 7, 2018 · 9e8cd03 · 9e8cd03
1 parent d87e2b5
commit 9e8cd03
Show file tree

Hide file tree

Showing 2 changed files with 10 additions and 2 deletions.
diff --git a/stdlib/LinearAlgebra/src/generic.jl b/stdlib/LinearAlgebra/src/generic.jl
@@ -109,8 +109,14 @@ julia> cross(a,b)
  0
 ```
 """
-cross(a::AbstractVector, b::AbstractVector) =
- [a[2]*b[3]-a[3]*b[2], a[3]*b[1]-a[1]*b[3], a[1]*b[2]-a[2]*b[1]]
+function cross(a::AbstractVector, b::AbstractVector)
+ if !(length(a) == length(b) == 3)
+ throw(DimensionMismatch("cross product is only defined for vectors of length 3"))
+ end
+ a1, a2, a3 = a
+ b1, b2, b3 = b
+ [a2*b3-a3*b2, a3*b1-a1*b3, a1*b2-a2*b1]
+end
 
 """
  triu(M)

diff --git a/stdlib/LinearAlgebra/test/generic.jl b/stdlib/LinearAlgebra/test/generic.jl
@@ -159,6 +159,8 @@ end
 @test !issymmetric(fill(1,5,3))
 @test !ishermitian(fill(1,5,3))
 @test (x = fill(1,3); cross(x,x) == zeros(3))
+@test_throws DimensionMismatch cross(fill(1,3), fill(1,4))
+@test_throws DimensionMismatch cross(fill(1,2), fill(1,3))
 
 @test trace(Bidiagonal(fill(1,5),fill(0,4),:U)) == 5