private static IEnumerable <int> GenDigits()
{
var k = 1;
var n1 = new GmpInteger(4);
var n2 = new GmpInteger(3);
var d = new GmpInteger(1);
var u = new GmpInteger();
var v = new GmpInteger();
var w = new GmpInteger(0);
while (true)
{
// digit
u.Div(n1, d);
v.Div(n2, d);
if (u.Cmp(v) == 0)
{
yield return(u.IntValue());
// extract
u.Mul(u, -10);
u.Mul(u, d);
n1.Mul(n1, 10);
n1.Add(n1, u);
n2.Mul(n2, 10);
n2.Add(n2, u);
}
else
{
// produce
var k2 = k * 2;
u.Mul(n1, k2 - 1);
v.Add(n2, n2);
w.Mul(n1, k - 1);
n1.Add(u, v);
u.Mul(n2, k + 2);
n2.Add(w, u);
d.Mul(d, k2 + 1);
k++;
}
}
}
public int Cmp(GmpInteger op1) => mpz_cmp(ref pointer, ref op1.pointer);
public void Div(GmpInteger op1, GmpInteger op2) => mpz_tdiv_q(ref pointer, ref op1.pointer, ref op2.pointer);
public void Sub(GmpInteger op1, GmpInteger op2) => mpz_sub(ref pointer, ref op1.pointer, ref op2.pointer);
public void Add(GmpInteger op1, GmpInteger op2) => mpz_add(ref pointer, ref op1.pointer, ref op2.pointer);
public void Mul(GmpInteger src, int val) => mpz_mul_si(ref pointer, ref src.pointer, val);
public void Mul(GmpInteger op1, GmpInteger op2) => mpz_mul(ref pointer, ref op1.pointer, ref op2.pointer);