Make scalar multiplication type stable (#900)

* Make scalar multiplication type stable

Also provide a unary + operator.

* Add tests for inferring linear algebra

* We cannot infer for Julia 1.1

* Add more @inferred tests

* New version 1.1.2

Author: eschnett

Project.toml

@@ -1,6 +1,6 @@
 name = "StaticArrays"
 uuid = "90137ffa-7385-5640-81b9-e52037218182"
-version = "1.1.1"
+version = "1.1.2"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

src/linalg.jl

@@ -4,6 +4,7 @@ import Base: +, -, *, /, \
 # Vector space algebra
 
 # Unary ops
+@inline +(a::StaticArray) = map(+, a)
 @inline -(a::StaticArray) = map(-, a)
 
 # Binary ops
@@ -17,11 +18,11 @@ import Base: +, -, *, /, \
 @inline -(a::StaticArray, b::AbstractArray) = map(-, a, b)
 
 # Scalar-array
-@inline *(a::Number, b::StaticArray) = broadcast(*, a, b)
-@inline *(a::StaticArray, b::Number) = broadcast(*, a, b)
+@inline *(a::Number, b::StaticArray) = map(c->a*c, b)
+@inline *(a::StaticArray, b::Number) = map(c->c*b, a)
 
-@inline /(a::StaticArray, b::Number) = broadcast(/, a, b)
-@inline \(a::Number, b::StaticArray) = broadcast(\, a, b)
+@inline /(a::StaticArray, b::Number) = map(c->c/b, a)
+@inline \(a::Number, b::StaticArray) = map(c->a\c, b)
 
 
 # With UniformScaling

test/linalg.jl

@@ -19,7 +19,10 @@ StaticArrays.similar_type(::Union{RotMat2,Type{RotMat2}}) = SMatrix{2,2,Float64,
 
         @test @inferred(v1 * c) === @SVector [4,8,12,16]
         @test @inferred(v1 / c) === @SVector [1.0,2.0,3.0,4.0]
-        @test @inferred(c \ v1)::SVector ≈ @SVector [1.0,2.0,3.0,4.0]
+        @test @inferred(c \ v1)::SVector === @SVector [1.0,2.0,3.0,4.0]
+
+        @test @inferred(+v1) === @SVector [+2,+4,+6,+8]
+        @test @inferred(-v1) === @SVector [-2,-4,-6,-8]
 
         @test @inferred(v1 + v2) === @SVector [6, 7, 8, 9]
         @test @inferred(v1 - v2) === @SVector [-2, 1, 4, 7]
@@ -36,6 +39,16 @@ StaticArrays.similar_type(::Union{RotMat2,Type{RotMat2}}) = SMatrix{2,2,Float64,
         #@test @inferred(v3 + v2) === @SVector [6, 7, 8, 9]
         #@test @inferred(v1 - v4) === @SVector [-2, 1, 4, 7]
         #@test @inferred(v3 - v2) === @SVector [-2, 1, 4, 7]
+
+        if VERSION ≥ v"1.2"
+            # #899 matrix-of-matrix
+            A = SMatrix{1,1}([1])
+            B = SMatrix{1,1}([A])
+            @test @inferred(1.0 * B) === SMatrix{1, 1, SMatrix{1, 1, Float64, 1}, 1}(B)
+            @test @inferred(1.0 \ B) === SMatrix{1, 1, SMatrix{1, 1, Float64, 1}, 1}(B)
+            @test @inferred(B * 1.0) === SMatrix{1, 1, SMatrix{1, 1, Float64, 1}, 1}(B)
+            @test @inferred(B / 1.0) === SMatrix{1, 1, SMatrix{1, 1, Float64, 1}, 1}(B)
+        end
     end
 
     @testset "Interaction with `UniformScaling`" begin