fix JuliaMath#95

Author: ziyiyin97

Diff for: ext/AbstractFFTsChainRulesCoreExt.jl

@@ -30,10 +30,10 @@ function ChainRulesCore.rrule(::typeof(rfft), x::AbstractArray{<:Real}, dims)
     halfdim = first(dims)
     d = size(x, halfdim)
     n = size(y, halfdim)
-    scale = reshape(
+    scale = typeof(y)(reshape(
         [i == 1 || (i == n && 2 * (i - 1) == d) ? 1 : 2 for i in 1:n],
         ntuple(i -> i == first(dims) ? n : 1, Val(ndims(x))),
-    )
+    ))
 
     project_x = ChainRulesCore.ProjectTo(x)
     function rfft_pullback(ȳ)
@@ -72,10 +72,10 @@ function ChainRulesCore.rrule(::typeof(irfft), x::AbstractArray, d::Int, dims)
     n = size(x, halfdim)
     invN = AbstractFFTs.normalization(y, dims)
     twoinvN = 2 * invN
-    scale = reshape(
+    scale = typeof(y)(reshape(
         [i == 1 || (i == n && 2 * (i - 1) == d) ? invN : twoinvN for i in 1:n],
         ntuple(i -> i == first(dims) ? n : 1, Val(ndims(x))),
-    )
+    ))
 
     project_x = ChainRulesCore.ProjectTo(x)
     function irfft_pullback(ȳ)
@@ -111,10 +111,10 @@ function ChainRulesCore.rrule(::typeof(brfft), x::AbstractArray, d::Int, dims)
     # compute scaling factors
     halfdim = first(dims)
     n = size(x, halfdim)
-    scale = reshape(
+    scale = typeof(y)(reshape(
         [i == 1 || (i == n && 2 * (i - 1) == d) ? 1 : 2 for i in 1:n],
         ntuple(i -> i == first(dims) ? n : 1, Val(ndims(x))),
-    )
+    ))
 
     project_x = ChainRulesCore.ProjectTo(x)
     function brfft_pullback(ȳ)