Jeff Delmerico wrote:
>
> 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.
>
> Thanks,
> Jeff Delmerico
>
options("digits") # 7
options(digits=x)
I may be mistaken, but I think the values are indeed exported
as double precision -- the issue here is just a display setting.
Ben Bolker
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