Merge pull request #486 from JuliaHealth/fix-rotation

Fix sum of `Grad`s

Author: pvillacorta

KomaMRIBase/src/datatypes/sequence/Grad.jl

@@ -226,12 +226,12 @@ Base.zero(::Type{Grad}) = Grad(0.0, 0.0)
 # Rotation
 Base.zero(::Grad) = Grad(0.0, 0.0)
 *(α::Real, x::Grad) = Grad(α * x.A, x.T, x.rise, x.fall, x.delay)
-+(x::Grad, y::Grad) = Grad(x.A .+ y.A, x.T, x.rise, x.fall, x.delay)
++(x::Grad, y::Grad) = Grad(x.A .+ y.A, max(x.T, y.T), max(x.rise, y.rise), max(x.fall, y.fall), max(x.delay, y.delay)) #TODO: solve this in a better way (by "stacking" gradients) issue #487
 # Others
 *(x::Grad, α::Real) = Grad(α * x.A, x.T, x.rise, x.fall, x.delay)
 /(x::Grad, α::Real) = Grad(x.A / α, x.T, x.rise, x.fall, x.delay)
 -(x::Grad) = -1 * x
--(x::Grad, y::Grad) = Grad(x.A .- y.A, x.T, x.rise, x.fall, x.delay)
+-(x::Grad, y::Grad) = Grad(x.A .- y.A, max(x.T, y.T), max(x.rise, y.rise), max(x.fall, y.fall), max(x.delay, y.delay)) #TODO: solve this in a better way (by "stacking" gradients) issue #487
 
 # Gradient functions
 function vcat(x::Array{Grad,1}, y::Array{Grad,1})

KomaMRIBase/test/runtests.jl

@@ -34,7 +34,11 @@ using TestItems, TestItemRunner
         R = rotz(θ)
         s2 = R*s #Matrix-Matrix{Grad} multiplication
         GR2 = R*s.GR.A #Matrix-vector multiplication
-        @test s2.GR.A ≈ GR2
+        @test s2.GR.A    ≈ GR2
+        @test s.GR.T     == s2.GR.T
+        @test s.GR.delay == s2.GR.delay
+        @test s.GR.rise  == s2.GR.rise
+        @test s.GR.fall  == s2.GR.fall
         # Rotation 3D case
         T, t1, t2, t3 = rand(4)
         N = 100
@@ -47,8 +51,11 @@ using TestItems, TestItemRunner
         R = Rx*Ry*Rz
         s2 = R*s #Matrix-Matrix{Grad} multiplication
         GR2 = R*s.GR.A #Matrix-vector multiplication
-        @test s2.GR.A ≈ GR2
-
+        @test s2.GR.A    ≈ GR2
+        @test s.GR.T     == s2.GR.T
+        @test s.GR.delay == s2.GR.delay
+        @test s.GR.rise  == s2.GR.rise
+        @test s.GR.fall  == s2.GR.fall
         # Concatenation of sequences
         A1, A2, A3, T1 = rand(4)
         s1 = Sequence([Grad(A1,T1);