mpfr_lib.mpfr_get_d_2exp Method (Int32, mpfr_t, mpfr_rnd

mpfr_libmpfr_get_d_2exp Method (Int32, mpfr_t, mpfr_rnd_t)

Return d and set exp such that 0.5 ≤ abs(d) <1 and d * 2^exp = op rounded to double precision, 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

C++

Copy

public static double mpfr_get_d_2exp(
	ref int exp,
	mpfr_t op,
	mpfr_rnd_t rnd
)

Public Shared Function mpfr_get_d_2exp ( 
	ByRef exp As Integer,
	op As mpfr_t,
	rnd As mpfr_rnd_t
) As Double

public:
static double mpfr_get_d_2exp(
	int% exp, 
	mpfr_t^ op, 
	mpfr_rnd_t rnd
)

static member mpfr_get_d_2exp : 
        exp : int byref * 
        op : mpfr_t * 
        rnd : mpfr_rnd_t -> float

Parameters

exp: Type: SystemInt32
Pointer to returned exponent.
op: Type: Math.Mpfr.Nativempfr_t
The operand floating-point number.
rnd: Type: Math.Mpfr.Nativempfr_rnd_t
The rounding direction.

Return Value

Type: Double
The converted floating-point number.

Remarks

If op is zero, then a zero of the same sign (or an unsigned zero, if the implementation does not have signed zeros) is returned, and exp is set to 0. If op is NaN or an infinity, then the corresponding double precision value is returned, and exp is undefined.

Examples

C++

Copy

// Create, initialize, and set a new floating-point number to -8.0
mpfr_t op = new mpfr_t();
mpfr_lib.mpfr_init2(op, 64U);
Assert.IsTrue(mpfr_lib.mpfr_set_d(op, -8.0, mpfr_rnd_t.MPFR_RNDN) == 0);

// Assert that the absolute value of op is 0.5 * 2^4.
int exp = 0;
Assert.IsTrue(mpfr_lib.mpfr_get_d_2exp(ref exp, op, mpfr_rnd_t.MPFR_RNDN) == -0.5);
Assert.IsTrue(exp == 4);

// Release unmanaged memory allocated for x and exp.
mpfr_lib.mpfr_clear(op);

' Create, initialize, and set a new floating-point number to -8.0
Dim op As mpfr_t = New mpfr_t()
mpfr_lib.mpfr_init2(op, 64U)
Assert.IsTrue(mpfr_lib.mpfr_set_d(op, -8.0, mpfr_rnd_t.MPFR_RNDN) = 0)

' Assert that the absolute value of op is 0.5 * 2^4.
Dim exp As Integer = 0
Assert.IsTrue(mpfr_lib.mpfr_get_d_2exp( exp,op,mpfr_rnd_t.MPFR_RNDN)  =  -0.5)
Assert.IsTrue(exp = 4)

' Release unmanaged memory allocated for x and exp.
mpfr_lib.mpfr_clear(op)

Parameters

Return Value

Reference