[R] Displaying numerics to full double precision

Jeff Delmerico jeffdelmerico at yahoo.com
Wed Dec 5 17:39:41 CET 2007

I'm working on a shared library of C functions for use with R, and I want to
create a matrix in R and pass it to the C routines.  I know R computes and
supposedly stores numerics in double precision, but when I create a matrix
of random numerics using rnorm(), the values are displayed in single
precision, and also exported in single precision when I pass them out to my
C routines.  An example is below:

> a <- matrix(rnorm(16, mean=10, sd=4), nrow=4)
> a
          [,1]      [,2]      [,3]      [,4]
[1,] 14.907606 17.572872 19.708977  9.809943
[2,]  9.322041 13.624452  7.745254  7.596176
[3,] 10.642408  6.151546  9.937434  6.913875
[4,] 14.617647  5.577073  8.217559 12.115465
> storage.mode(a)
[1] "double"

Does anyone know if there is a way to change the display or storage settings
so that the values will be displayed to their full precision?   Or does
rnorm only produce values to single precision? 

Any assistance would be greatly appreciated.

Jeff Delmerico
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