Correct inverse plan logic (#69)

* Correct inverse plan caching logic in test plans

* Use inv rather than plan_inv in scaled plan

Author: gaurav-arya

src/definitions.jl

@@ -278,7 +278,7 @@ plan_ifft(x::AbstractArray, region; kws...) =
 plan_ifft!(x::AbstractArray, region; kws...) =
     ScaledPlan(plan_bfft!(x, region; kws...), normalization(x, region))
 
-plan_inv(p::ScaledPlan) = ScaledPlan(plan_inv(p.p), inv(p.scale))
+plan_inv(p::ScaledPlan) = ScaledPlan(inv(p.p), inv(p.scale))
 
 LinearAlgebra.mul!(y::AbstractArray, p::ScaledPlan, x::AbstractArray) =
     LinearAlgebra.lmul!(p.scale, LinearAlgebra.mul!(y, p.p, x))

test/testplans.jl

@@ -27,21 +27,20 @@ end
 function AbstractFFTs.plan_bfft(x::AbstractArray{T}, region; kwargs...) where {T}
     return InverseTestPlan{T}(region, size(x))
 end
+
 function AbstractFFTs.plan_inv(p::TestPlan{T}) where {T}
     unscaled_pinv = InverseTestPlan{T}(p.region, p.sz)
-    unscaled_pinv.pinv = p
-    pinv = AbstractFFTs.ScaledPlan(
-        unscaled_pinv, AbstractFFTs.normalization(T, p.sz, p.region),
-    )
+    N = AbstractFFTs.normalization(T, p.sz, p.region)
+    unscaled_pinv.pinv = AbstractFFTs.ScaledPlan(p, N)
+    pinv = AbstractFFTs.ScaledPlan(unscaled_pinv, N)
     return pinv
 end
-function AbstractFFTs.plan_inv(p::InverseTestPlan{T}) where {T}
-    unscaled_pinv = TestPlan{T}(p.region, p.sz)
-    unscaled_pinv.pinv = p
-    pinv = AbstractFFTs.ScaledPlan(
-        unscaled_pinv, AbstractFFTs.normalization(T, p.sz, p.region),
-    )
-    return pinv
+function AbstractFFTs.plan_inv(pinv::InverseTestPlan{T}) where {T}
+    unscaled_p = TestPlan{T}(pinv.region, pinv.sz)
+    N = AbstractFFTs.normalization(T, pinv.sz, pinv.region)
+    unscaled_p.pinv = AbstractFFTs.ScaledPlan(pinv, N)
+    p = AbstractFFTs.ScaledPlan(unscaled_p, N)
+    return p
 end
 
 # Just a helper function since forward and backward are nearly identical
@@ -118,22 +117,23 @@ function AbstractFFTs.plan_inv(p::TestRPlan{T,N}) where {T,N}
     firstdim = first(p.region)::Int
     d = p.sz[firstdim]
     sz = ntuple(i -> i == firstdim ? d ÷ 2 + 1 : p.sz[i], Val(N))
+    _N = AbstractFFTs.normalization(T, p.sz, p.region)
+
     unscaled_pinv = InverseTestRPlan{T}(d, p.region, sz)
-    unscaled_pinv.pinv = p
-    pinv = AbstractFFTs.ScaledPlan(
-        unscaled_pinv, AbstractFFTs.normalization(T, p.sz, p.region),
-    )
+    unscaled_pinv.pinv = AbstractFFTs.ScaledPlan(p, _N)
+    pinv = AbstractFFTs.ScaledPlan(unscaled_pinv, _N)
     return pinv
 end
-function AbstractFFTs.plan_inv(p::InverseTestRPlan{T,N}) where {T,N}
-    firstdim = first(p.region)::Int
-    sz = ntuple(i -> i == firstdim ? p.d : p.sz[i], Val(N))
-    unscaled_pinv = TestRPlan{T}(p.region, sz)
-    unscaled_pinv.pinv = p
-    pinv = AbstractFFTs.ScaledPlan(
-        unscaled_pinv, AbstractFFTs.normalization(T, sz, p.region),
-    )
-    return pinv
+
+function AbstractFFTs.plan_inv(pinv::InverseTestRPlan{T,N}) where {T,N}
+    firstdim = first(pinv.region)::Int
+    sz = ntuple(i -> i == firstdim ? pinv.d : pinv.sz[i], Val(N))
+    _N = AbstractFFTs.normalization(T, sz, pinv.region)
+
+    unscaled_p = TestRPlan{T}(pinv.region, sz)
+    unscaled_p.pinv = AbstractFFTs.ScaledPlan(pinv, _N)
+    p = AbstractFFTs.ScaledPlan(unscaled_p, _N)
+    return p
 end
 
 Base.size(p::TestRPlan) = p.sz