[R] Division ?

[Martin Maechler]

>>>>> "TH" == Ted Harding <Ted.Harding at manchester.ac.uk>
>>>>>     on Sun, 03 May 2009 10:11:04 +0100 (BST) writes:

    TH> On 02-May-09 17:34:15, bogdanno wrote:
    >> It seems division with numbers bigger than 10 000 000
    >> doesn't work 20000000/21 [1] 952381
    >>> 55555555/23
    >> [1] 2415459
    >> 
    >> Thank you

    TH> I think you are confusing what is displayed with what is
    TH> computed:

    TH>   20000000/21 # [1] 952381 print(20000000/21,17) # [1]
    TH> 952380.9523809524

    TH>   55555555/23 # [1] 2415459 print(55555555/23,17) # [1]
    TH> 2415458.913043478

    TH>   (20000000/21)*21 # [1] 2e+07
    TH> print((20000000/21)*21,17) # [1] 2e+07

    TH>   (55555555/23)*23 # [1] 55555555
    TH> print((55555555/23)*23,17) # [1] 55555555

    TH> Your "numbers bigger than 10 000 000" corresponds to the
    TH> default display of results to 7 significant figures.

    TH> If (as in the above print() statements) you increase
    TH> this, you get more "reasonable"-looking results.

Yes, indeed.
If Bogdanno thinks he wants to always see "all" digits, he
should use something like

  options(digits= 20)

in his R startup setting, e.g. in his Rprofile, see  ?Startup.

Note however:  
     Quite a few experienced R users rather do  *REDUCE* the default number
     of digits printed, rather than enlarge them.
     (I don't)

Martin Maechler, ETH Zurich


    TH> --------------------------------------------------------------------
    TH> E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
    TH> Fax-to-email: +44 (0)870 094 0861 Date: 03-May-09 Time:
    TH> 10:11:02 ------------------------------ XFMail
    TH> ------------------------------