gmp_lib.mpn_sec_sub_1 Method

GMP Native Interface for .NET

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gmp_libmpn_sec_sub_1 Method
Set R to A - b, where R = {rp, n}, A = {ap, n}, and b is a single limb.

Namespace:  Math.Gmp.Native
Assembly:  Math.Gmp.Native (in Math.Gmp.Native.dll) Version: 1.0.0.0 (1.0.0.0)
Syntax
Copy
public static mp_limb_t mpn_sec_sub_1(
	mp_ptr rp,
	mp_ptr ap,
	mp_size_t n,
	mp_limb_t b,
	mp_ptr tp
)
Public Shared Function mpn_sec_sub_1 ( 
	rp As mp_ptr,
	ap As mp_ptr,
	n As mp_size_t,
	b As mp_limb_t,
	tp As mp_ptr
) As mp_limb_t
public:
static mp_limb_t mpn_sec_sub_1(
	mp_ptr^ rp, 
	mp_ptr^ ap, 
	mp_size_t n, 
	mp_limb_t b, 
	mp_ptr^ tp
)
static member mpn_sec_sub_1 : 
        rp : mp_ptr * 
        ap : mp_ptr * 
        n : mp_size_t * 
        b : mp_limb_t * 
        tp : mp_ptr -> mp_limb_t

Parameters

rp
Type: Math.Gmp.Nativemp_ptr
The result integer.
ap
Type: Math.Gmp.Nativemp_ptr
The first operand integer.
n
Type: Math.Gmp.Nativemp_size_t
The number of limbs of ap and rp.
b
Type: Math.Gmp.Nativemp_limb_t
The second operand integer.
tp
Type: Math.Gmp.Nativemp_ptr
The scratch operand integer.

Return Value

Type: mp_limb_t
Returns borrow, either 0 or 1.
Remarks

This function takes O(N) time, unlike the leaky functions mpn_sub_1 which is O(1) on average. It requires scratch space of mpn_sec_sub_1_itch(n) limbs, to be passed in the tp parameter. The scratch space requirements are guaranteed to be at most n limbs, and increase monotonously in the operand size.

Examples
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// Create multi-precision operands, and expected result.
mp_ptr ap = new mp_ptr(new uint[] { 0xffffffff, 0xffffffff });
mp_ptr result = new mp_ptr(new uint[] { 0xfffffffe, 0xffffffff });
mp_ptr rp = new mp_ptr(result.Size);

// Create scratch space.
mp_size_t size = gmp_lib.mpn_sec_sub_1_itch(ap.Size);
mp_ptr tp = new mp_ptr(size);

// Set rp = ap - 1.
mp_limb_t borrow = gmp_lib.mpn_sec_sub_1(rp, ap, ap.Size, 1, tp);

// Assert result of operation.
Assert.IsTrue(borrow == 0);
Assert.IsTrue(rp.SequenceEqual(result));

// Release unmanaged memory.
gmp_lib.free(rp, ap, tp, result);
' Create multi-precision operands, and expected result.
Dim ap As New mp_ptr(New UInteger() { &HffffffffUI, &HffffffffUI})
Dim result As New mp_ptr(New UInteger() { &HfffffffeUI, &HffffffffUI})
Dim rp As New mp_ptr(result.Size)

' Create scratch space.
Dim size As mp_size_t = gmp_lib.mpn_sec_sub_1_itch(ap.Size)
Dim tp As New mp_ptr(size)

' Set rp = ap - 1.
Dim borrow As mp_limb_t = gmp_lib.mpn_sec_sub_1(rp, ap, ap.Size, 1, tp)

' Assert result of operation.
Assert.IsTrue(borrow = 0)
Assert.IsTrue(rp.SequenceEqual(result))

' Release unmanaged memory.
gmp_lib.free(rp, ap, tp, result)

No code example is currently available or this language may not be supported.

No code example is currently available or this language may not be supported.

See Also
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