[R] Numerical accuracy

[Tuszynski, Jaroslaw W.]

I do not know about details of numerical accuracy of R, it is probable
related to numerical accuracy of C compiler that was used to compile it (gcc
?). 
However I would like to mention that I run into some problems with accuracy
of sum and cumsum functions. See:  
   >   x = c(1, 1e20, 1e40, -1e40, -1e20, -1)
   >   sum(x)
   [1] -1e+20
   >   cumsum(x)
   [1]  1e+00  1e+20  1e+40  0e+00 -1e+20 -1e+20
And wrote functions (with help of R-Help list) to address the problem. See
sum.exact and cumsum.exact in caTools package:
  >   sum.exact(x)
  [1] 0
  >   cumsum.exact(x)
  [1] 1e+00 1e+20 1e+40 1e+20 1e+00 0e+00
 
Jarek
====================================================\=======

 Jarek Tuszynski, PhD.                           o / \ 
 Science Applications International Corporation  <\__,|  
 (703) 676-4192                                   ">   \
 Jaroslaw.W.Tuszynski at saic.com                     `    \

 

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Talita Perciano Costa
Leite
Sent: Monday, June 27, 2005 10:57 AM
To: r-help at stat.math.ethz.ch
Subject: [R] Numerical accuracy

Hi people,

I need to prove the good quality of numerical accuracy of R. Anyone knows a
paper or anything else comparing R to other statistical softwares in terms
of numerical accuracy.
I've made a long search about that but I found nothing. Please help me!!

Thanx,

Talita Leite

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