loose of sign when using imap for mapping polynomials from o

I want to map some polynomials from the ring of reals to the ring of rationals, using imap.
Thus when using imap (or fetch), the sign of the polynomials in the new ring are not preserved, I always obtain only positive coefficients.
Here is the code example:
> ring r=real, (x,y), dp;
> poly f= -1+2x2+3y3-2x-3y;
> poly g= -1-2x2-3y3+x+3y;
> ideal m=f,g;
> ring t=0,(x,y),dp;
> ideal n=imap(r,m);
> n[1];
3y3+2x2+2x+3y+1
> n[2];
3y3+2x2+x+3y+1
> poly newf=imap(r,f);
> poly newg=imap(r,g);
> newf;
3y3+2x2+2x+3y+1
> newg;
3y3+2x2+x+3y+1

I would really appreciate if someone could give me some hints on how to preserve the sign of the original coefficients in the new ring (and if someone can explain me what happens).

thanks you in advance,
madalina

If you specify the number of decimal places while defining the ring, then there is no problem:

ring r=(real,10), (x,y), dp;

I do not know why the problem occurs, but this works. See Section 3.3.1 of the Singular manual for the syntax.

thank you, the conversion is working now,
madalina