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_lib.mpfr_atan2 Method
Set rop to the arc-tangent2 of y and x rounded in the direction rnd.

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_atan2(
	mpfr_t rop,
	mpfr_t y,
	mpfr_t x,
	mpfr_rnd_t rnd
)

Parameters

rop
Type: Math.Mpfr.Native.mpfr_t
The result floating-point number.
y
Type: Math.Mpfr.Native.mpfr_t
The ordinate floating-point value.
x
Type: Math.Mpfr.Native.mpfr_t
The abscissa floating-point value.
rnd
Type: Math.Mpfr.Native.mpfr_rnd_t
The rounding direction.

Return Value

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

If x > 0, atan2(y, x) = atan(y/x); if x < 0, atan2(y, x) = sign(y) * (Pi - atan(abs(y/x))), thus a number from -Pi to Pi. As for atan, in case the exact mathematical result is +Pi or -Pi, its rounded result might be outside the function output range.

atan2(y, 0) does not raise any floating-point exception. Special values are handled as described in the ISO C99 and IEEE 754-2008 standards for the atan2 function:

  • atan2(+0, -0) returns +Pi.
  • atan2(-0, -0) returns -Pi.
  • atan2(+0, +0) returns +0.
  • atan2(-0, +0) returns -0.
  • atan2(+0, x) returns +Pi for x < 0.
  • atan2(-0, x) returns -Pi for x < 0.
  • atan2(+0, x) returns +0 for x > 0.
  • atan2(-0, x) returns -0 for x > 0.
  • atan2(y, 0) returns -Pi/2 for y < 0.
  • atan2(y, 0) returns +Pi/2 for y > 0.
  • atan2(+Inf, -Inf) returns +3 * Pi/4.
  • atan2(-Inf, -Inf) returns -3 * Pi/4.
  • atan2(+Inf, +Inf) returns +Pi/4.
  • atan2(-Inf, +Inf) returns -Pi/4.
  • atan2(+Inf, x) returns +Pi/2 for finite x.
  • atan2(-Inf, x) returns -Pi/2 for finite x.
  • atan2(y, -Inf) returns +Pi for finite y > 0.
  • atan2(y, -Inf) returns -Pi for finite y < 0.
  • atan2(y, +Inf) returns +0 for finite y > 0.
  • atan2(y, +Inf) returns -0 for finite y < 0.
Examples
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// Create, initialize, and set a new floating-point number x to -1.
mpfr_t x = new mpfr_t();
mpfr_lib.mpfr_init2(x, 64U);
Assert.IsTrue(mpfr_lib.mpfr_set_si(x, -1, mpfr_rnd_t.MPFR_RNDN) == 0);

// Create, initialize, and set a new floating-point number y to 0.
mpfr_t y = new mpfr_t();
mpfr_lib.mpfr_init2(y, 64U);
Assert.IsTrue(mpfr_lib.mpfr_set_si(y, 0, mpfr_rnd_t.MPFR_RNDN) == 0);

// Create and initialize a new floating-point number rop.
mpfr_t rop = new mpfr_t();
mpfr_lib.mpfr_init2(rop, 64U);

// Set rop = atan2(y, x).
Assert.IsTrue(mpfr_lib.mpfr_atan2(rop, y, x, mpfr_rnd_t.MPFR_RNDN) == 1);

// Assert that the value of rop is PI.
Assert.IsTrue(mpfr_lib.mpfr_const_pi(x, mpfr_rnd_t.MPFR_RNDN) == 1);
Assert.IsTrue(mpfr_lib.mpfr_cmp(rop, x) == 0);

// Release unmanaged memory allocated for x, y, and rop.
mpfr_lib.mpfr_clears(x, y, rop, null);
See Also