Different numerical results between sparse and full matrices

[Michael Goffioul]

Hi,

While investigating some the remaining test errors I have when
building octave with MSVC, I found a behavior difference between
sparse and full matrices, which boils down to the following example
(see result of "sparse(x)./sparse(0)"):

========

octave.exe:26> x = 1+1i
x =  1 + 1i

octave.exe:27> x/0
warning: division by zero
ans = Inf + Infi

octave.exe:28> sparse(x)./sparse(0)
ans = Compressed Column Sparse (rows = 1, cols = 1, nnz = 1 [100%])

  (1, 1) -> NaN + NaNi        <<<<<<<< THIS IS WHERE THE PROBLEM IS

octave.exe:29> sparse(x)./0
warning: division by zero
ans = Compressed Column Sparse (rows = 1, cols = 1, nnz = 1 [100%])

  (1, 1) -> Inf + Infi

octave.exe:31> sparse(real(x))./sparse(0)
ans = Compressed Column Sparse (rows = 1, cols = 1, nnz = 1 [100%])

  (1, 1) -> Inf

========

In other words, complex division by 0 in sparse matrices gives NaN
instead of Inf. Does anybody know where I should look at to find where
this could come from?

Michael.