math.ldexp Method (Single, Int32)

mathldexp Method (Single, Int32)

Scales the specified floating-point number by 2^exponent.

Namespace: C
Assembly: C.math (in C.math.dll) Version: 1.0.0.0 (1.0.0.0)

Syntax

public static float ldexp(
	float number,
	int exponent
)

Public Shared Function ldexp ( 
	number As Single,
	exponent As Integer
) As Single

public:
static float ldexp(
	float number, 
	int exponent
)

static member ldexp : 
        number : float32 * 
        exponent : int -> float32

Parameters

number: Type: SystemSingle
A floating-point number.
exponent: Type: SystemInt32
The exponent of the power of two.

Return Value

Type: Single
The value number * 2^exponent.

Remarks

Special values are treated as follows.

If number is ±0, it is returned.
If number is infinite, it is returned.
If exponent is 0, number is returned.
If number is NaN, NaN is returned.

The function ldexp(Single, Int32) ("load exponent"), together with its dual, frexp(Single, Int32), can be used to manipulate the representation of a floating-point number without direct bit manipulations.

The function ldexp(Single, Int32) is equivalent to scalbn(Single, Int32).

See ldexp in the C standard documentation.

Examples

C++

Copy

Assert.IsTrue(math.ldexp(0.8F, 4) == 12.8F);
Assert.IsTrue(math.ldexp(-0.854375F, 5) == -27.34F);
Assert.IsTrue(math.ldexp(1F, 0) == 1F);

Assert.IsTrue(math.ldexp(math.FLT_MIN / 2F, 0) == math.FLT_MIN / 2F);
Assert.IsTrue(math.ldexp(math.FLT_MIN / 2F, 1) == math.FLT_MIN);
Assert.IsTrue(math.ldexp(math.FLT_MIN * 1.5F, -math.FLT_MANT_BITS) == 2F * math.FLT_DENORM_MIN);
Assert.IsTrue(math.ldexp(math.FLT_MIN * 1.5F, -math.FLT_MANT_BITS - 1) == math.FLT_DENORM_MIN);
Assert.IsTrue(math.ldexp(math.FLT_MIN * 1.25F, -math.FLT_MANT_BITS) == math.FLT_DENORM_MIN);
Assert.IsTrue(math.ldexp(math.FLT_MIN * 1.25F, -math.FLT_MANT_BITS - 1) == math.FLT_DENORM_MIN);

Assert.IsTrue(math.ldexp(1F, System.Int32.MaxValue) == System.Single.PositiveInfinity);
Assert.IsTrue(math.ldexp(1F, System.Int32.MinValue) == 0F);
Assert.IsTrue(math.ldexp(-1F, System.Int32.MaxValue) == System.Single.NegativeInfinity);
Assert.IsTrue(math.ldexp(-1F, System.Int32.MinValue) == -0F);

Assert.IsTrue(math.ldexp(0.8F, 4) = 12.8F);
Assert.IsTrue(math.ldexp(-0.854375F, 5) = -27.34F);
Assert.IsTrue(math.ldexp(1F, 0) = 1F);

Assert.IsTrue(math.ldexp(math.FLT_MIN / 2F, 0) = math.FLT_MIN / 2F);
Assert.IsTrue(math.ldexp(math.FLT_MIN / 2F, 1) = math.FLT_MIN);
Assert.IsTrue(math.ldexp(math.FLT_MIN * 1.5F, -math.FLT_MANT_BITS) = 2F * math.FLT_DENORM_MIN);
Assert.IsTrue(math.ldexp(math.FLT_MIN * 1.5F, -math.FLT_MANT_BITS - 1) = math.FLT_DENORM_MIN);
Assert.IsTrue(math.ldexp(math.FLT_MIN * 1.25F, -math.FLT_MANT_BITS) = math.FLT_DENORM_MIN);
Assert.IsTrue(math.ldexp(math.FLT_MIN * 1.25F, -math.FLT_MANT_BITS - 1) = math.FLT_DENORM_MIN);

Assert.IsTrue(math.ldexp(1F, System.Int32.MaxValue) = System.Single.PositiveInfinity);
Assert.IsTrue(math.ldexp(1F, System.Int32.MinValue) = 0F);
Assert.IsTrue(math.ldexp(-1F, System.Int32.MaxValue) = System.Single.NegativeInfinity);
Assert.IsTrue(math.ldexp(-1F, System.Int32.MinValue) = -0F);

Reference

math Class

ldexp Overload

C Namespace