MPFR Native Interface for .NET
Math.Mpfr.Native
mpfr_lib Class
mpfr_lib Methods
mpfr_abs Method
mpfr_acos Method
mpfr_acosh Method
mpfr_add Method
mpfr_add_d Method
mpfr_add_q Method
mpfr_add_si Method
mpfr_add_ui Method
mpfr_add_z Method
mpfr_agm Method
mpfr_ai Method
mpfr_asin Method
mpfr_asinh Method
mpfr_asprintf Method
mpfr_atan Method
mpfr_atan2 Method
mpfr_atanh Method
mpfr_beta Method
mpfr_buildopt_decimal_p Method
mpfr_buildopt_float128_p Method
mpfr_buildopt_gmpinternals_p Method
mpfr_buildopt_sharedcache_p Method
mpfr_buildopt_tls_p Method
mpfr_buildopt_tune_case Method
mpfr_can_round Method
mpfr_cbrt Method
mpfr_ceil Method
mpfr_check_range Method
mpfr_clear Method
mpfr_clear_divby0 Method
mpfr_clear_erangeflag Method
mpfr_clear_flags Method
mpfr_clear_inexflag Method
mpfr_clear_nanflag Method
mpfr_clear_overflow Method
mpfr_clear_underflow Method
mpfr_clears Method
mpfr_cmp Method
mpfr_cmp_d Method
mpfr_cmp_f Method
mpfr_cmp_q Method
mpfr_cmp_si Method
mpfr_cmp_si_2exp Method
mpfr_cmp_ui Method
mpfr_cmp_ui_2exp Method
mpfr_cmp_z Method
mpfr_cmpabs Method
mpfr_const_catalan Method
mpfr_const_euler Method
mpfr_const_log2 Method
mpfr_const_pi Method
mpfr_copysign Method
mpfr_cos Method
mpfr_cosh Method
mpfr_cot Method
mpfr_coth Method
mpfr_csc Method
mpfr_csch Method
mpfr_custom_clear Method
mpfr_custom_get_exp Method
mpfr_custom_get_kind Method
mpfr_custom_get_significand Method
mpfr_custom_get_size Method
mpfr_custom_init Method
mpfr_custom_init_set Method
mpfr_custom_move Method
mpfr_d_div Method
mpfr_d_sub Method
mpfr_digamma Method
mpfr_dim Method
mpfr_div Method
mpfr_div_2exp Method
mpfr_div_2si Method
mpfr_div_2ui Method
mpfr_div_d Method
mpfr_div_q Method
mpfr_div_si Method
mpfr_div_ui Method
mpfr_div_z Method
mpfr_divby0_p Method
mpfr_eint Method
mpfr_eq Method
mpfr_equal_p Method
mpfr_erandom Method
mpfr_erangeflag_p Method
mpfr_erf Method
mpfr_erfc Method
mpfr_exp Method
mpfr_exp10 Method
mpfr_exp2 Method
mpfr_expm1 Method
mpfr_fac_ui Method
mpfr_fits_intmax_p Method
mpfr_fits_sint_p Method
mpfr_fits_slong_p Method
mpfr_fits_sshort_p Method
mpfr_fits_uint_p Method
mpfr_fits_uintmax_p Method
mpfr_fits_ulong_p Method
mpfr_fits_ushort_p Method
mpfr_flags_clear Method
mpfr_flags_restore Method
mpfr_flags_save Method
mpfr_flags_set Method
mpfr_flags_test Method
mpfr_floor Method
mpfr_fma Method
mpfr_fmma Method
mpfr_fmms Method
mpfr_fmod Method
mpfr_fmodquo Method
mpfr_fms Method
mpfr_fpif_export Method
mpfr_fpif_import Method
mpfr_fprintf Method
mpfr_frac Method
mpfr_free_cache Method
mpfr_free_cache2 Method
mpfr_free_pool Method
mpfr_free_str Method
mpfr_frexp Method
mpfr_gamma Method
mpfr_gamma_inc Method
mpfr_get_d Method
mpfr_get_d_2exp Method
mpfr_get_default_prec Method
mpfr_get_default_rounding_mode Method
mpfr_get_emax Method
mpfr_get_emax_max Method
mpfr_get_emax_min Method
mpfr_get_emin Method
mpfr_get_emin_max Method
mpfr_get_emin_min Method
mpfr_get_exp Method
mpfr_get_f Method
mpfr_get_flt Method
mpfr_get_patches Method
mpfr_get_prec Method
mpfr_get_q Method
mpfr_get_si Method
mpfr_get_sj Method
mpfr_get_str Method
mpfr_get_ui Method
mpfr_get_uj Method
mpfr_get_version Method
mpfr_get_z Method
mpfr_get_z_2exp Method
mpfr_grandom Method
mpfr_greater_p Method
mpfr_greaterequal_p Method
mpfr_hypot Method
mpfr_inexflag_p Method
mpfr_inf_p Method
mpfr_init Method
mpfr_init_set Method
mpfr_init_set_d Method
mpfr_init_set_f Method
mpfr_init_set_q Method
mpfr_init_set_si Method
mpfr_init_set_str Method
mpfr_init_set_ui Method
mpfr_init_set_z Method
mpfr_init2 Method
mpfr_inits Method
mpfr_inits2 Method
mpfr_inp_str Method
mpfr_integer_p Method
mpfr_j0 Method
mpfr_j1 Method
mpfr_jn Method
mpfr_less_p Method
mpfr_lessequal_p Method
mpfr_lessgreater_p Method
mpfr_lgamma Method
mpfr_li2 Method
mpfr_lngamma Method
mpfr_log Method
mpfr_log_ui Method
mpfr_log10 Method
mpfr_log1p Method
mpfr_log2 Method
mpfr_max Method
mpfr_min Method
mpfr_min_prec Method
mpfr_modf Method
mpfr_mp_memory_cleanup Method
mpfr_mul Method
mpfr_mul_2exp Method
mpfr_mul_2si Method
mpfr_mul_2ui Method
mpfr_mul_d Method
mpfr_mul_q Method
mpfr_mul_si Method
mpfr_mul_ui Method
mpfr_mul_z Method
mpfr_nan_p Method
mpfr_nanflag_p Method
mpfr_neg Method
mpfr_nextabove Method
mpfr_nextbelow Method
mpfr_nexttoward Method
mpfr_nrandom Method
mpfr_number_p Method
mpfr_out_str Method
mpfr_overflow_p Method
mpfr_pow Method
mpfr_pow_si Method
mpfr_pow_ui Method
mpfr_pow_z Method
mpfr_prec_round Method
mpfr_print_rnd_mode Method
mpfr_printf Method
mpfr_rec_sqrt Method
mpfr_regular_p Method
mpfr_reldiff Method
mpfr_remainder Method
mpfr_remquo Method
mpfr_rint Method
mpfr_rint_ceil Method
mpfr_rint_floor Method
mpfr_rint_round Method
mpfr_rint_roundeven Method
mpfr_rint_trunc Method
mpfr_root Method
mpfr_rootn_ui Method
mpfr_round Method
mpfr_roundeven Method
mpfr_sec Method
mpfr_sech Method
mpfr_set Method
mpfr_set_d Method
mpfr_set_default_prec Method
mpfr_set_default_rounding_mode Method
mpfr_set_divby0 Method
mpfr_set_emax Method
mpfr_set_emin Method
mpfr_set_erangeflag Method
mpfr_set_exp Method
mpfr_set_f Method
mpfr_set_flt Method
mpfr_set_inexflag Method
mpfr_set_inf Method
mpfr_set_nan Method
mpfr_set_nanflag Method
mpfr_set_overflow Method
mpfr_set_prec Method
mpfr_set_prec_raw Method
mpfr_set_q Method
mpfr_set_si Method
mpfr_set_si_2exp Method
mpfr_set_sj Method
mpfr_set_sj_2exp Method
mpfr_set_str Method
mpfr_set_ui Method
mpfr_set_ui_2exp Method
mpfr_set_uj Method
mpfr_set_uj_2exp Method
mpfr_set_underflow Method
mpfr_set_z Method
mpfr_set_z_2exp Method
mpfr_set_zero Method
mpfr_setsign Method
mpfr_sgn Method
mpfr_si_div Method
mpfr_si_sub Method
mpfr_signbit Method
mpfr_sin Method
mpfr_sin_cos Method
mpfr_sinh Method
mpfr_sinh_cosh Method
mpfr_snprintf Method
mpfr_sprintf Method
mpfr_sqr Method
mpfr_sqrt Method
mpfr_sqrt_ui Method
mpfr_strtofr Method
mpfr_sub Method
mpfr_sub_d Method
mpfr_sub_q Method
mpfr_sub_si Method
mpfr_sub_ui Method
mpfr_sub_z Method
mpfr_subnormalize Method
mpfr_sum Method
mpfr_swap Method
mpfr_tan Method
mpfr_tanh Method
mpfr_trunc Method
mpfr_ui_div Method
mpfr_ui_pow Method
mpfr_ui_pow_ui Method
mpfr_ui_sub Method
mpfr_underflow_p Method
mpfr_unordered_p Method
mpfr_urandom Method
mpfr_urandomb Method
mpfr_vasprintf Method
MPFR_VERSION_NUM Method
mpfr_vfprintf Method
mpfr_vprintf Method
mpfr_vsnprintf Method
mpfr_vsprintf Method
mpfr_y0 Method
mpfr_y1 Method
mpfr_yn Method
mpfr_z_sub Method
mpfr_zero_p Method
mpfr_zeta Method
mpfr_zeta_ui Method
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mpfr_libmpfr_prec_round Method
Round x according to rnd with precision prec, which must be an integer between MPFR_PREC_MIN and MPFR_PREC_MAX (otherwise the behavior is undefined).

Namespace:  Math.Mpfr.Native
Assembly:  Math.Mpfr.Native (in Math.Mpfr.Native.dll) Version: 1.0.0.0 (1.0.0.0)
Syntax
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public static int mpfr_prec_round(
	mpfr_t x,
	mpfr_prec_t prec,
	mpfr_rnd_t rnd
)

Parameters

x
Type: Math.Mpfr.Nativempfr_t
The operand floating-point number.
prec
Type: Math.Mpfr.Nativempfr_prec_t
The precision in bits.
rnd
Type: Math.Mpfr.Nativempfr_rnd_t
The rounding direction.

Return Value

Type: Int32
Return zero, a positive, or a negative value if x is respectively equal to, greater than, or lower than the exact result. See GNU MPFR - Rounding Modes for details.
Remarks

If prec is greater or equal to the precision of x, then new space is allocated for the significand, and it is filled with zeros. Otherwise, the significand is rounded to precision prec with the given direction. In both cases, the precision of x is changed to prec.

Here is an example of how to use mpfr_prec_round to implement Newton’s algorithm to compute the inverse of a, assuming x is already an approximation to n bits:

C#
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mpfr_set_prec (t, 2 * n);
mpfr_set(t, a, mpfr_rnd_t.MPFR_RNDN);            /* round a to 2n bits */
mpfr_mul(t, t, x, mpfr_rnd_t.MPFR_RNDN);         /* t is correct to 2n bits */
mpfr_ui_sub(t, 1, t, mpfr_rnd_t.MPFR_RNDN);      /* high n bits cancel with 1 */
mpfr_prec_round(t, n, mpfr_rnd_t.MPFR_RNDN);     /* t is correct to n bits */
mpfr_mul(t, t, x, mpfr_rnd_t.MPFR_RNDN);         /* t is correct to n bits */
mpfr_prec_round(x, 2 * n, mpfr_rnd_t.MPFR_RNDN); /* exact */
mpfr_add(x, x, t, mpfr_rnd_t.MPFR_RNDN);         /* x is correct to 2n bits */

Warning! You must not use this function if x was initialized with mpfr_custom_init_set (see GNU MPFR - Custom Interface).

Examples
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// Create and initialize a new floating-point number x with 64-bit precision.
mpfr_t x = new mpfr_t();
mpfr_lib.mpfr_init2(x, 64U);

// Round x to precision 128 bits.
Assert.IsTrue(mpfr_lib.mpfr_prec_round(x, 128U, mpfr_rnd_t.MPFR_RNDN) == 0);

// Assert that precision has changed to 128 bits.
Assert.IsTrue(mpfr_lib.mpfr_get_prec(x) == 128U);

// Release unmanaged memory allocated for x.
mpfr_lib.mpfr_clear(x);
See Also