big

Documentation

Index

• type Int
  • func NewInt(x int64) *Int
  • func (z *Int) Abs(x *Int) *Int
  • func (z *Int) Add(x, y *Int) *Int
  • func (x *Int) BitLen() int
  • func (x *Int) Cmp(y *Int) (r int)
  • func (z *Int) Div(x, y *Int) *Int
  • func (z *Int) Exp(x, y, m *Int) *Int
  • func (x *Int) FillBytes(buf []byte) []byte
  • func (z *Int) GCD(x, y, a, b *Int) *Int
  • func (z *Int) Mod(x, y *Int) *Int
  • func (z *Int) ModInverse(g, n *Int) *Int
  • func (z *Int) Mul(x, y *Int) *Int
  • func (z *Int) Neg(x *Int) *Int
  • func (z *Int) QuoRem(x, y, r *Int) (*Int, *Int)
  • func (z *Int) Set(x *Int) *Int
  • func (z *Int) SetBytes(buf []byte) *Int
  • func (z *Int) SetInt64(x int64) *Int
  • func (z *Int) SetUint64(x uint64) *Int
  • func (x *Int) Sign() int
  • func (z *Int) Sub(x, y *Int) *Int
• type Word

Types

type Int

type Int struct {
	// contains filtered or unexported fields
}

An Int represents a signed multi-precision integer. The zero value for an Int represents the value 0.

Operations always take pointer arguments (*Int) rather than Int values, and each unique Int value requires its own unique *Int pointer. To "copy" an Int value, an existing (or newly allocated) Int must be set to a new value using the Int.Set method; shallow copies of Ints are not supported and may lead to errors.

func NewInt

func NewInt(x int64) *Int

NewInt allocates and returns a new Int set to x.

func (*Int) Abs

func (z *Int) Abs(x *Int) *Int

Abs sets z to |x| (the absolute value of x) and returns z.

func (*Int) Add

func (z *Int) Add(x, y *Int) *Int

Add sets z to the sum x+y and returns z.

func (*Int) BitLen

func (x *Int) BitLen() int

BitLen returns the length of the absolute value of x in bits. The bit length of 0 is 0.

func (*Int) Cmp

func (x *Int) Cmp(y *Int) (r int)

Cmp compares x and y and returns:

-1 if x <  y
 0 if x == y
+1 if x >  y

func (*Int) Div

func (z *Int) Div(x, y *Int) *Int

Div sets z to the quotient x/y for y != 0 and returns z. If y == 0, a division-by-zero run-time panic occurs. Div implements Euclidean division (unlike Go); see DivMod for more details.

func (*Int) Exp

func (z *Int) Exp(x, y, m *Int) *Int

Exp sets z = x**y mod |m| (i.e. the sign of m is ignored), and returns z. If m == nil or m == 0, z = x**y unless y <= 0 then z = 1. If m != 0, y < 0, and x and m are not relatively prime, z is unchanged and nil is returned.

Modular exponentiation of inputs of a particular size is not a cryptographically constant-time operation.

func (*Int) FillBytes

func (x *Int) FillBytes(buf []byte) []byte

FillBytes sets buf to the absolute value of x, storing it as a zero-extended big-endian byte slice, and returns buf.

If the absolute value of x doesn't fit in buf, FillBytes will panic.

func (*Int) GCD

func (z *Int) GCD(x, y, a, b *Int) *Int

GCD sets z to the greatest common divisor of a and b and returns z. If x or y are not nil, GCD sets their value such that z = a*x + b*y.

a and b may be positive, zero or negative. (Before Go 1.14 both had to be > 0.) Regardless of the signs of a and b, z is always >= 0.

If a == b == 0, GCD sets z = x = y = 0.

If a == 0 and b != 0, GCD sets z = |b|, x = 0, y = sign(b) * 1.

If a != 0 and b == 0, GCD sets z = |a|, x = sign(a) * 1, y = 0.

func (*Int) Mod

func (z *Int) Mod(x, y *Int) *Int

Mod sets z to the modulus x%y for y != 0 and returns z. If y == 0, a division-by-zero run-time panic occurs. Mod implements Euclidean modulus (unlike Go); see DivMod for more details.

func (*Int) ModInverse

func (z *Int) ModInverse(g, n *Int) *Int

ModInverse sets z to the multiplicative inverse of g in the ring ℤ/nℤ and returns z. If g and n are not relatively prime, g has no multiplicative inverse in the ring ℤ/nℤ. In this case, z is unchanged and the return value is nil.

func (*Int) Mul

func (z *Int) Mul(x, y *Int) *Int

Mul sets z to the product x*y and returns z.

func (*Int) Neg

func (z *Int) Neg(x *Int) *Int

Neg sets z to -x and returns z.

func (*Int) QuoRem

func (z *Int) QuoRem(x, y, r *Int) (*Int, *Int)

QuoRem sets z to the quotient x/y and r to the remainder x%y and returns the pair (z, r) for y != 0. If y == 0, a division-by-zero run-time panic occurs.

QuoRem implements T-division and modulus (like Go):

q = x/y      with the result truncated to zero
r = x - y*q

(See Daan Leijen, “Division and Modulus for Computer Scientists”.) See DivMod for Euclidean division and modulus (unlike Go).

func (*Int) Set

func (z *Int) Set(x *Int) *Int

Set sets z to x and returns z.

func (*Int) SetBytes

func (z *Int) SetBytes(buf []byte) *Int

SetBytes interprets buf as the bytes of a big-endian unsigned integer, sets z to that value, and returns z.

func (*Int) SetInt64

func (z *Int) SetInt64(x int64) *Int

SetInt64 sets z to x and returns z.

func (*Int) SetUint64

func (z *Int) SetUint64(x uint64) *Int

SetUint64 sets z to x and returns z.

func (*Int) Sign

func (x *Int) Sign() int

Sign returns:

-1 if x <  0
 0 if x == 0
+1 if x >  0

func (*Int) Sub

func (z *Int) Sub(x, y *Int) *Int

Sub sets z to the difference x-y and returns z.

type Word

type Word uint

A Word represents a single digit of a multi-precision unsigned integer.