// SetNum sets the numerator of z returning z
//
// NB this isn't part of math/big which uses Num().Set() for this
// purpose. In gmp Num() returns a copy hence the need for a SetNum()
// method.
func (z *Rat) SetNum(a *Int) *Rat {
z.doinit()
a.doinit()
C.mpq_set_num(&z.i[0], &a.i[0])
C.mpq_canonicalize(&z.i[0])
return z
}
// IsInt returns true if the denominator of x is 1.
func (q *Rat) IsInt() bool {
q.doinit()
C.mpq_canonicalize(&q.i[0])
if q.Denom().Cmp(intOne) == 0 {
return true
}
return false
}
// SetFrac sets z to a/b and returns z.
func (z *Rat) SetFrac(a, b *Int) *Rat {
z.doinit()
a.doinit()
b.doinit()
// FIXME copying? or referencing?
C.mpq_set_num(&z.i[0], &a.i[0])
C.mpq_set_den(&z.i[0], &b.i[0])
C.mpq_canonicalize(&z.i[0])
return z
}
// SetDenom sets the numerator of z returning z
//
// NB this isn't part of math/big which uses Num().Set() for this
// purpose. In gmp Num() returns a copy hence the need for a SetNum()
// method.
func (z *Rat) SetDenom(a *Int) *Rat {
z.doinit()
a.doinit()
C.mpq_set_den(&z.i[0], &a.i[0])
// If numerator is zero don't canonicalize
if C._mpq_num_sgn(&z.i[0]) != 0 {
C.mpq_canonicalize(&z.i[0])
}
return z
}
// SetFrac64 sets q to x/y and returns q.
func (q *Rat) SetFrac64(x int64, y int64) *Rat {
q.doinit()
// y has to be positive for mpq_set_si
if y < 0 {
x *= -1
y *= -1
}
C.mpq_set_si(&q.i[0], C.long(x), C.ulong(y))
C.mpq_canonicalize(&q.i[0])
return q
}
// SetStringBase interprets s as a number in the given base
// and sets z to that value. The base must be in the range [2,36].
// SetString returns an error if s cannot be parsed or the base is invalid.
func (q *Rat) SetStringBase(s string, base int) (*Rat, bool) {
q.doinit()
if base < 2 || base > 36 {
return nil, false
}
p := C.CString(s)
defer C.free(unsafe.Pointer(p))
if C.mpq_set_str(&q.i[0], p, C.int(base)) < 0 {
return nil, false
}
C.mpq_canonicalize(&q.i[0])
return q, true
}
// SetFrac64 sets z to a/b and returns z.
func (z *Rat) SetFrac64(a, b int64) *Rat {
z.doinit()
if b == 0 {
panic("division by zero")
}
// Detect overflow if running on 32 bits
if a == int64(C.long(a)) && b == int64(C.long(b)) {
if b < 0 {
a = -a
b = -b
}
C.mpq_set_si(&z.i[0], C.long(a), C.ulong(b))
C.mpq_canonicalize(&z.i[0])
if b < 0 {
// This only happens when b = 1<<63
z.Neg(z)
}
} else {
// Slow path but will work on 32 bit architectures
z.SetFrac(NewInt(a), NewInt(b))
}
return z
}
// SetUint sets q to x/y and returns q.
func (q *Rat) SetUint(x, y uint) *Rat {
q.doinit()
C.mpq_set_ui(&q.i[0], C.ulong(x), C.ulong(y))
C.mpq_canonicalize(&q.i[0])
return q
}
// SetString sets z to the value of s and returns z and a boolean indicating
// success. s can be given as a fraction "a/b" or as a floating-point number
// optionally followed by an exponent. If the operation failed, the value of
// z is undefined but the returned value is nil.
func (z *Rat) SetString(s string) (*Rat, bool) {
if len(s) == 0 {
return nil, false
}
z.doinit()
a := new(Int)
b := new(Int)
// check for a quotient
sep := strings.Index(s, "/")
if sep >= 0 {
// FIXME Num and Denom are bust
// if _, ok := z.Num().SetString(s[0:sep], 10); !ok {
// return nil, false
// }
// if _, ok := z.Denom().SetString(s[sep+1:], 10); !ok {
// return nil, false
// }
if _, ok := a.SetString(s[0:sep], 10); !ok {
return nil, false
}
if _, ok := b.SetString(s[sep+1:], 10); !ok {
return nil, false
}
z.SetFrac(a, b)
C.mpq_canonicalize(&z.i[0])
return z, true
}
// check for a decimal point
sep = strings.Index(s, ".")
// check for an exponent
e := strings.IndexAny(s, "eE")
exp := new(Int)
if e >= 0 {
if e < sep {
// The E must come after the decimal point.
return nil, false
}
if _, ok := exp.SetString(s[e+1:], 10); !ok {
return nil, false
}
s = s[0:e]
}
if sep >= 0 {
s = s[0:sep] + s[sep+1:]
exp.Sub(exp, NewInt(int64(len(s)-sep)))
}
if _, ok := a.SetString(s, 10); !ok {
return nil, false
}
absExp := new(Int).Abs(exp)
powTen := new(Int).Exp(_Int10, absExp, nil)
if exp.Sign() < 0 {
b = powTen
} else {
a.Mul(a, powTen)
b.SetInt64(1)
}
z.SetFrac(a, b)
C.mpq_canonicalize(&z.i[0])
return z, true
}
