[R] About the multiprecision computing package in R

J C Nash
Sat, 14 Mar 2020 20:34:57 -0000

The issue is to avoid the storage and operational penalty. 100 x 100 matrix in
100 decimals vs 100 x 100 matrix in 50
decimals for many operations like copy, scale, etc. But accumulation of inner
products, you want to avoid digit loss,
e.g., A and B are long vectors -- say 100000 long, with a few "large"
elements but most smaller. However 99000 "small"
numbers could add up and ...

As with many such issues, it doesn't affect the vast majority of
occurrences. Indeed few of my own. IEEE arithmetic
usually does the job (I was one of the members of the original committee). This
particular
concern arose when trying to tease out a signal from a great deal of noise from
a spacecraft sensor.

JN


On 2020-03-14 4:28 p.m., Jeff Newmiller wrote:
> Not sure I understand the concern. IEEE 754 double precision floating point
was invented to allow for avoiding loss of precision when manipulating single
precision floating point numbers... but then C just ignores single precision and
you are expected to know that the precision of your answers may only be relied
on at single precision for certain operations.
>
> Wouldn't you just set Rmpfr precision to double your actual desired
precision and move on? Though I suppose you might consider  more than doubling
the desired precision to deal with exponentiation [1].
>
> [1] https://en.m.wikipedia.org/wiki/Extended_precision#Working_range
>
> On March 14, 2020 1:10:19 PM PDT, J C Nash <profjcnash at gmail.com>
wrote:
>> Rmpfr does "support" matrix algebra, but I have been trying
for some
>> time to determine if it computes "double" precision (i.e.,
double the
>> set level of precision) inner products. I suspect that it does NOT,
>> which is unfortunate. However, I would be happy to be wrong about
>> this.
>>
>> JN
>>
>> On 2020-03-14 3:41 p.m., Bert Gunter wrote:
>>> Read its documentation yourself and unless you have good reason not
>> to,
>>> always cc the list (which I have done here).
>>>
>>>
>>> Bert Gunter
>>>
>>> "The trouble with having an open mind is that people keep
coming
>> along and
>>> sticking things into it."
>>> -- Opus (aka Berkeley Breathed in his "Bloom County"
comic strip )
>>>
>>>
>>> On Sat, Mar 14, 2020 at 12:28 PM ??? <13917987541 at 163.com>
wrote:
>>>
>>>> Thanks. Does it support matrix algebra?
>>>>
>>>>
>>>>
>>>> ???
>>>> ???13917987541 at 163.com
>>>>
>>>>
>>
<https://maas.mail.163.com/dashi-web-extend/html/proSignature.html?iconUrl=http%3A%2F%2Fmail-online.nosdn.127.net%2F17c23bc1722125aa6261c33736f525c5.jpg&name=%E6%9E%97%E4%BC%9F%E7%92%90&uid=13917987541%40163.com&ftlId=1&items=%5B%22%E9%82%AE%E7%AE%B1%EF%BC%9A13917987541%40163.com%22%5D>
>>>>
>>>> ??? ??????
<https://mail.163.com/dashi/dlpro.html?from=mail88> ??
>>>>
>>>> On 03/15/2020 03:18, Bert Gunter <bgunter.4567 at
gmail.com> wrote:
>>>> Use google instead, as I recommended. If that's impossible
in China,
>> you
>>>> should state that and what you tried (Baidu) in your query.
>>>>
>>>> You'll get the Rmpfr package.
>>>>
>>>> Bert Gunter
>>>>
>>>> "The trouble with having an open mind is that people keep
coming
>> along and
>>>> sticking things into it."
>>>> -- Opus (aka Berkeley Breathed in his "Bloom County"
comic strip )
>>>>
>>>>
>>>> On Sat, Mar 14, 2020 at 11:48 AM ??? <13917987541 at
163.com> wrote:
>>>>
>>>>> Thanks, I tried Baidu but get nothing
>>>>>
>>>>>
>>>>>
>>>>> ???
>>>>> ???13917987541 at 163.com
>>>>>
>>>>>
>>
<https://maas.mail.163.com/dashi-web-extend/html/proSignature.html?iconUrl=http%3A%2F%2Fmail-online.nosdn.127.net%2F17c23bc1722125aa6261c33736f525c5.jpg&name=%E6%9E%97%E4%BC%9F%E7%92%90&uid=13917987541%40163.com&ftlId=1&items=%5B%22%E9%82%AE%E7%AE%B1%EF%BC%9A13917987541%40163.com%22%5D>
>>>>>
>>>>> ??? ??????
<https://mail.163.com/dashi/dlpro.html?from=mail88> ??
>>>>>
>>>>> On 03/15/2020 02:44, Bert Gunter <bgunter.4567 at
gmail.com> wrote:
>>>>> Here's a novel idea:
>>>>> Do a google search on "multiprecision computing
package R" for an
>> answer.
>>>>>
>>>>> Bert Gunter
>>>>>
>>>>> "The trouble with having an open mind is that people
keep coming
>> along
>>>>> and sticking things into it."
>>>>> -- Opus (aka Berkeley Breathed in his "Bloom
County" comic strip )
>>>>>
>>>>>
>>>>> On Sat, Mar 14, 2020 at 10:36 AM ??? <13917987541 at
163.com> wrote:
>>>>>
>>>>>> Dear all
>>>>>>
>>>>>>
>>>>>> I need a multiprecision computing package in R, if
anyone in the
>> list
>>>>>> knows, please let me known...
>>>>>>
>>>>>>
>>>>>> Many thanks
>>>>>>
>>>>>>
>>>>>> Weilu Lin
>>>>>>         [[alternative HTML version deleted]]
>>>>>>
>>>>>> ______________________________________________
>>>>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE
and more, see
>>>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>>>> PLEASE do read the posting guide
>>>>>> http://www.R-project.org/posting-guide.html
>>>>>> and provide commented, minimal, self-contained,
reproducible code.
>>>>>>
>>>>>
>>>
>>> 	[[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more,
see
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>