>From the help page for "Foreign"
> ?Foreign
Numeric vectors in R will be passed as type double * to C (and as double
precision to Fortran)
Also, see the help page for "double"
> ?double
R has no single precision data type. All real numbers are stored in double
precision format.
The functions as.single and single are identical to as.double and double
except they set
the attribute Csingle that is used in the .C and .Fortran interface, and they
are intended
only to be used in that context.
HTH
Steven McKinney, Ph.D.
Statistician
Molecular Oncology and Breast Cancer Program
British Columbia Cancer Research Centre
email: smckinney +at+ bccrc +dot+ ca
tel: 604-675-8000 x7561
BCCRC
Molecular Oncology
675 West 10th Ave, Floor 4
Vancouver B.C.
V5Z 1L3
Canada
-----Original Message-----
From: r-help-boun...@r-project.org on behalf of mau...@alice.it
Sent: Mon 3/30/2009 3:07 AM
To: r-help@r-project.org
Cc: John C. Nash
Subject: [R] what is R equivalent of Fortran DOUBLE PRECISION ?
I noticed taht R cannot understand certain Fortran real constant formats. For
instance:
c14 <- as.double( 7.785205408500864D-02)
Error: unexpected symbol in " c14 <- as.double( 7.785205408500864D"
The above "D" is used in Fortran language to indicate the memory starage mode.
That is for instructing Fortran compiler
to store such a REAL constant in DOUBLE PRECISION... am I right ?
Since R cannot undestand numerical conatant post-fixed by the letter "D", I
wonder how I can instruct R interpreter to
store such a numerical constant reserving as muh memory as necessary so as to
accommodate a double precision number.
I noticed R accepts the folllowing syntax but I do not know if i have achieved
my goal thsi way:
> c14 <- as.double( 7.785205408500864E-02)
> typeof(c4)
[1] "double"
My questions are: what is the best precision I can get with R when dealing with
real number ?
Is R "double" type equvalent to Fortran DOUBLE PRECISION for internal number
representation ?
Thank you very much.
Maura
tutti i telefonini TIM!
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