Rick White wrote:
On 24 Jun 2004, Todd Miller wrote:
On Thu, 2004-06-24 at 06:14, Curzio Basso wrote:
I noticed that when multiplying two matrices of type Float32, the result is Float64:
I modified dot() and innerproduct() this morning to return Float32 and Complex32 for like inputs.
I wonder whether it would be worth providing an option to accumulate the sums using Float64 and to convert to Float32 before storing them in an array. I suspect that one reason this returned Float64 is that it is very easy to run into precision/roundoff problems in single-precision matrix multiplies. You could avoid that by using doubles for the sum while still returning the result as a single. Rick
I definitely agree. I'm pretty certain the reason it was done with double precision floats is the sensitivity to roundoff issues with matrix operations. I think Rick is right though that only intermediate calculations need to be done in double precision and that doesn't require the whole output array to be kept that way. Perry