[Rd] C function, double problem

Rui Barradas ruipbarradas at sapo.pt
Sat Dec 8 16:47:27 CET 2012


The double in R and the double in C are the same type, with the same 
number of decimals (64 bits), so it's not because the numbers are too long.
Try calling .C("function", other parameters, result = double(quantity)).
Or maybe the error is in the C code, of which we know nothing about.

Rui Barradas
Em 08-12-2012 02:26, mpietro escreveu:
> Hi everybody,
> here's my problem:
> i call a C function which calculates a large number of double values and
> puts them into an array which is passed from R as a parameter in the
> function (like  .C("function", other parameters, result =  as.double( c ( 1
> : quantity ) ).
> When the values come back to R in the result array, they are all truncated
> to their integer value (i.e. I lose the decimal parts).
> I think that the problem is that this calculated double numbers are actually
> too long, with many decimals, because i changed in code  the calculated
> values with arbitrary double values with a few decimals and it works.
> Has anybody any idea of where the problem is?
> Thanks in advance!
> --
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