Laboratoire de l'Informatique et du Parallélisme » Pobyso

from sage.rings.real_mpfr cimport *

#

# Two functions to manipulate the real RealNumber values.

#

# Get the address of the value of a RealNumber. This address can be

# used to to set the value as well.

#

cpdef int get_rn_value(RealNumber x):

    return(<int>&(x.value))

#

# We use the "array trick" to workaround the pointer dereferencing

# issue (in Cython there is no unary operator "*").

#

cpdef set_rn_value(RealNumber x, int p, mp_rnd_t rnd=GMP_RNDN):

    mpfr_set(x.value, (<mpfr_t *>p)[0], rnd)

#

# Do not use this function!

# It changes the precision of the instance behind the curtain, but precision is

# class attribute. If the precision is increased, memory space is wasted and

# other problems may surface in subsequent operations.

# If the precision is decreased the semantics

# are broken since the expected precision (from the class attribute) is not

# the actual precision.

#

cpdef s_rn_value(RealNumber x, int p):

    mpfr_clear(x.value)

    mpfr_init2(x.value, mpfr_get_prec((<mpfr_t *>p)[0]))

    #x.__prec = mpfr_get_prec(x.value)

    printf("x.value prec: %d\n", mpfr_get_prec(x.value))

    mpfr_set(x.value, (<mpfr_t *>p)[0], GMP_RNDN)

#

# Compare two RN with the mpfr_cmp function

cpdef cmp_rn_value(RealNumber x, RealNumber y):

    return(mpfr_cmp(x.value, y.value))