[R] how to calculate a numeric's digits count?

[David L Carlson]

Where do these numbers come from? If they are calculated values, they are actually many decimal places longer than your examples. They are represented on your terminal with fewer decimals according to the setting of options("digits"). 

For example:

> sqrt(2)*sqrt(2)
[1] 2
> sqrt(2)*sqrt(2) == 2  
[1] FALSE
# FAQ 7.31 Why doesn’t R think these numbers are equal?
> options("digits")
$digits
[1] 7
> options(digits=22)
> sqrt(2)*sqrt(2)
[1] 2.000000000000000444089

If the numbers were read from a plain text file and you are talking about how they are represented in the file, analyze them as character strings.

-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of PO SU
Sent: Thursday, October 23, 2014 10:35 PM
To: R. Help
Subject: [R] how to calculate a numeric's digits count?


Dear usRers,
  Now i want to cal ,e.g. 
 cal(1.234)  will get 3
 cal(1) will get 0
 cal(1.3045) will get 4
 But the difficult part is cal(1.3450) will get 4 not 3.
So, is there anyone happen to know the solution to this problem, or it can't be solved in R, because 1.340 will always be transformed autolly to 1.34?






--

PO SU
mail: desolator88 at 163.com 
Majored in Statistics from SJTU
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