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Hi,

It depends. You have the choice or using the Cython variable as follows

from sage.rings.real_mpfr cimport RealNumber
from sage.rings.real_mpfr import RR

cdef RealNumber my_number = RR(4)
...

Or you can use pure C as follows

cdef mpfr_t value
...

It might help to have a look at how the real number are implemented in Sage in the files

Hi,

It depends. You have the choice or of using ~~the~~ a Cython variable as follows

from sage.rings.real_mpfr cimport RealNumber
from sage.rings.real_mpfr import RR

cdef RealNumber my_number = RR(4)
RR(5.634)
...

Or you can use pure C as follows

cdef mpfr_t value
mpfr_init2(value, 53)
mpfr_set_flt(value, 5.364, MPFR_RNDN)
...

Anyway, in the latter case, it is not possible to write value = 5 because there is no cast from int to mpfr_t (those are C variables)!

It might help to have a look at how the real number are implemented in Sage in the files