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Re: Motion P1788/M0009.01_ExactDotProduct

Michel Hack wrote:

Arnold Neumaier wrote:

The Zhu/Hayes paper quoted by Demmel shows that one can do the computations
with a single pass through the data in an online fashion, with a storage
that only in the worst case takes the length of the accumulator needed for
the exact dot product.


In other words, it uses a software implementation of a complete format,
albeit one that is adaptive, and avoids the cost of a fixed allocation
for the worst case. 

No, only the leading part of the complete format is ever assembled.
One never gets to know the 100th digit of the complete result.


Arnold Neumaier