Display exact value of a variable in R

Question

> x <- 1.00042589212565
> x
[1] 1.000426

If I wanted to print the exact value of x, how would I do it?

Sorry if this is a dumb question. I tried Googling for "R" and "exact" or "round" but all I get are articles about how to round.

Thank you in advance!

If it isn't a whole number then you won't get an exact value, just an approximation. See http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f — Richie Cotton, Jul 18 '13 at 14:27
*exactly* The only truly exact value is the 8-bytes of a mantissa/exponent encoded floating-point value. — Spacedman, Jul 18 '13 at 15:06

score 12 · Accepted Answer · answered Jul 18 '13 at 13:11

12

Globally solution during all the session

options(digits=16)
> x
[1] 1.00042589212565

or locally just for x:

sprintf("%.16f", x)
[1] "1.0004258921256499"

answered Jul 18 '13 at 13:11

agstudy

3

I like the second one, which shows nicely that "exact" is relative. – Roland Jul 18 '13 at 14:06

score 8 · Answer 2 · answered Jul 18 '13 at 13:11

8

print(x, digits=15)

or

format(x, digits=15)

or

sprintf("%.14f", x)

answered Jul 18 '13 at 13:11

Hong Ooi

2 Answers2