Why Intel decimal library?

[Paul Dale]

(03-12-2014 01:18 AM)Claudio L. Wrote:  I guess I'll have to download and compile the Intel library to see how large it is. We only have 2 MB of flash, but if the library is that good, perhaps it will be worth the extra space.

Don't bother it won't fit. Not even close. The 34S mathematics library and decNumber will fit easily.


I used decNumber internally for a couple of reasons. The decNumber library I used didn't support decimal64 and decimal128 directly for arithmetic operations and there are the packing and unpacking steps to consider. I also wanted the increased precision to give me some room to round better. Having extra guard digits during a computation is a godsend.


The comparison you mentioned seems flawed in other ways too. For example, it doesn't seem to mention what decNumber settings were used to get their timings? How many digits e.g. If you look at the functions that really matter (addition, multiplication and to a lesser degree division) the timings aren't so different. The format conversions are where the big differences are and they aren't important at all, these are done very rarely. I also notice square root isn't there. The IEEE standard requires this to be correctly rounded and the decNumber method works perfectly but isn't overly fast.


- Pauli