Update toeplitzplans.jl

src/toeplitzplans.jl

@@ -21,7 +21,7 @@ ToeplitzPlan{T}(v, tmp::Array{S,N}, dft::Plan{S}, idft::Plan{S}, dims) where {T,
 
 
 divdimby2(d::Int, sz1, szs...) = isone(d) ? ((sz1 + 1) ÷ 2, szs...) : (sz1, divdimby2(d-1, szs...)...)
-muldimby2(d::Int, sz1, szs...) = isone(d) ? (2sz1 - 1, szs...) : (sz1, muldimby2(d-1, szs...)...)
+muldimby2(d::Int, sz1, szs...) = isone(d) ? (max(0,2sz1 - 1), szs...) : (sz1, muldimby2(d-1, szs...)...)
 
 function toeplitzplan_size(dims, szs)
     ret = szs
@@ -89,17 +89,23 @@ function uppertoeplitz_padvec(v::AbstractVector{T}) where T
     tmp
 end
 
-uppertoeplitz_vecs(v, dims::AbstractVector, szs) = [fft!(uppertoeplitz_padvec(v[1:szs[d]])) for d in dims]
+safe_fft!(A) = isempty(A) ? A : fft!(A)
+
+uppertoeplitz_vecs(v, dims::AbstractVector, szs) = [safe_fft!(uppertoeplitz_padvec(v[1:szs[d]])) for d in dims]
 uppertoeplitz_vecs(v, dims::Tuple{}, szs) = ()
-uppertoeplitz_vecs(v, dims::Tuple, szs) = (fft!(uppertoeplitz_padvec(v[1:szs[first(dims)]])), uppertoeplitz_vecs(v, tail(dims), szs)...)
-uppertoeplitz_vecs(v, d::Int, szs) = (fft!(uppertoeplitz_padvec(v[1:szs[d]])),)
+uppertoeplitz_vecs(v, dims::Tuple, szs) = (safe_fft!(uppertoeplitz_padvec(v[1:szs[first(dims)]])), uppertoeplitz_vecs(v, tail(dims), szs)...)
+uppertoeplitz_vecs(v, d::Int, szs) = (safe_fft!(uppertoeplitz_padvec(v[1:szs[d]])),)
+
+
+# allow FFT to work by making sure tmp is non-empty
+safe_tmp(tmp::AbstractArray{<:Any,N}) where N = isempty(tmp) ? similar(tmp, ntuple(_ -> 1, Val(N))...) : tmp
 
 function plan_uppertoeplitz!(v::AbstractVector{T}, szs::NTuple{N,Int}, dim=ntuple(identity,Val(N))) where {T,N}
     S = complex(float(T))
 
     tmp = zeros(S, to_toeplitzplan_size(dim, szs)...)
-    dft = plan_fft!(tmp, dim)
-    idft = plan_ifft!(similar(tmp), dim)
+    dft = plan_fft!(safe_tmp(tmp), dim)
+    idft = plan_ifft!(safe_tmp(similar(tmp)), dim)
 
     return ToeplitzPlan{float(T)}(uppertoeplitz_vecs(v, dim, szs), tmp, dft, idft, dim)
 end