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mpfr_libmpfr_frexp Method (ptrmpfr_exp_t, mpfr_t, mpfr_t, mpfr_rnd_t)
Set exp and y such that 0.5 ≤ abs(y) < 1 and y * 2^exp = x rounded to the precision of y, using the given rounding mode.

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_frexp(
	ptr<mpfr_exp_t> exp,
	mpfr_t y,
	mpfr_t x,
	mpfr_rnd_t rnd
)

Parameters

exp
Type: Math.Gmp.Nativeptrmpfr_exp_t
The returned exponent.
y
Type: Math.Mpfr.Nativempfr_t
The returned significand.
x
Type: Math.Mpfr.Nativempfr_t
The operand floating-point number.
rnd
Type: Math.Mpfr.Nativempfr_rnd_t
The rounding direction.

Return Value

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

If x is zero, then y is set to a zero of the same sign and exp is set to 0. If x is NaN or an infinity, then y is set to the same value and exp is undefined.

Examples
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// Create, initialize, and set a new floating-point number x to 100.
mpfr_t x = new mpfr_t();
mpfr_lib.mpfr_init2(x, 64U);
Assert.IsTrue(mpfr_lib.mpfr_set_si(x, 100, mpfr_rnd_t.MPFR_RNDN) == 0);

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

// Initialize exponent.
ptr<mpfr_exp_t> exp = new ptr<mpfr_exp_t>(0);

// Find y and exp such that x = y * 2^exp where y in [0.5, 1).
Assert.IsTrue(mpfr_lib.mpfr_frexp(exp, y, x, mpfr_rnd_t.MPFR_RNDN) == 0);

// Assert the value of exp and y.
Assert.IsTrue(y.ToString() == "0.781250000000000000000e0" && exp.Value == 7);

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