Effects of newly introduced -mpcX 80387 precision flag

[Bradley Lucier]

On May 3, 2007, at 2:45 PM, Uros Bizjak wrote:

>
> Bradley Lucier wrote:
>>
>> On May 3, 2007, at 11:11 AM, Uros Bizjak wrote:
>>
>>> Could you please post a patch with suggested wording about this  
>>> option (I was trying to write something similar to the warning  
>>> that icc has in its documentation about precision settings).
>>
>> How about this?  It perhaps reflects my own biases, but the term  
>> "catastrophic loss of accuracy" is sometimes used in the technical  
>> sense that I mean here.  For the performance figures, I used the  
>> figures you gave in your e-mail but add "or more" to be on the  
>> safe side.
> What about "significant loss of accuracy" as these options probably  
> won't cause a nuclear reactor meltdown ;)

Well, I did some googling, and the technical term I was thinking of  
was "catastrophic cancellation".  So how about

Note that some mathematical routines in such libraries could suffer  
significant loss of accuracy, typically through so-called  
"catastrophic cancellation", when this option is used to set the  
precision to less than extended precision.

Brad