I think you will find that the 'catastrophic loss of significance' is in
the printing at the default level. Try print(x, digits=15).
On Sun, 3 Aug 2008, cls59 wrote:
Hello all,
I have a quick question about formatting date strings..
Datetime strings, methinks. If you do just want days, use as.Date not
as.POSIXct.
I am currently debugging some Matlab code someone else wrote and since it is
so bad that I have to go through it line by line I figured that I would just
rewrite the thing in R.
The code produces plots of wave spectra with decimal days since the Epoch as
the x axis and wave period as the Y axis. I am able to convert the date
stamp in the input file to a POSIXct object with the following call:
date = as.POSIXct(header[[1]][2],tz='GMT',format='%Y%m%d_%k')
date
"2008-07-11 03:00:00 GMT"
So every thing looks groovy, using as.double(date) gives me the number of
seconds since the epoch which reproduces the correct date when fed to date
-u -r on the command line.
However, I can't seem to find a clean way of converting the date to decimal
days since the epoch. Using
as.double(date)/86400
Gives:
14071.12
Which is a catastrophic loss of significance, the number should be 14071.125
I tried playing around with the format command to see if I could get R to
format the date differently, but no luck.
Any suggestions?
-Charlie
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Brian D. Ripley, [EMAIL PROTECTED]
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