Re: Information
Can someone please clarify or confirm to me how we view
the EDP? In particular, the only practical difference I see
between the EDP and a correctly rounded dot product
(the present state of P-1788's plan) is that a possible
EDP operation must return some representation of
the exact result (not a standard floating point number),
whereas the correctly rounded dot product must return
a floating point number the same AS IF the dot product
were first computed exactly, then rounded according to
the rounding mode in effect.
Thus, if my interpretation is right, the only additional requirement
of the EDP over the correctly rounded DP is that a representation
from which the exact result can be recovered be available. Wouldn't
whether or not that result is subsequently rounded into a floating point
number then be up to the programmer or user?
Baker
On 09/05/2013 06:27 AM, Vincent Lefevre wrote:
On 2013-09-05 12:35:14 +0200, Ulrich Kulisch wrote:
Just for your information:
http://download-software.intel.com/sites/default/files/319433-015.pdf
provides information about future Intel processors. Among others
there will be 32 vector registers of 512 Bit.
With these CA may or may not be a question of clever coding.
I fear that you would spend most of the time in conversions between
FP and these registers: you still need to store the FP to memory,
extract the components (sign, significand, exponent), determine the
position of the significand in the accumulator, possibly split the
significand, add the significand (1 or 2 parts) to the registers,
and detect/do the possible carry propagation. Then, what is the
effect on the pipeline?
Before including such non-conventional operations in a standard,
comparisons with alternative solutions (e.g. purely FP based) must
be done.
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R. Baker Kearfott, rbk@xxxxxxxxxxxxx (337) 482-5346 (fax)
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Department of Mathematics, University of Louisiana at Lafayette
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Box 4-1010, Lafayette, LA 70504-1010, USA
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