public void MulTenTest()
{
var a = new ALong(10);
a.MulBase(5);
a += 10;
Assert.IsTrue(a == "1000010");
}
public void MulTenTest()
{
var a = new ALong(10);
a.MulBase(5);
a += 10;
Assert.IsTrue(a == "1000010");
}
/// <summary>
/// Calculates a product of a two ALong instances, a.k.a "School" method (very slow)
/// </summary>
/// <param name="num1">Multiplicand</param>
/// <param name="num2">Multiplier</param>
/// <returns>Product of num1 and num2.</returns>
//TODO: replace with Karatsuba, Schönhage–Strassen or Knuth. (Fast Fourier transform?).
//TODO: use base of size of Int32 to "shorten" sizes of numbers within multiplication speed being kept.
public static ALong Mul(ALong num1, ALong num2)
{
var result = new ALong(0);
if (num1 == 0 || num2 == 0) { return result; }
var carry = 0;
for (int i = 0; i < num1.Length(); i++)
{
var n1 = num1.GetRNumAtIndex(i);
var res = String.Empty;
var n2len = num2.Length();
carry = 0;
for (int k = 0; k < n2len; k++)
{
var n2 = num2.GetRNumAtIndex(k);
var ns = n1 * n2 + carry;
carry = ns / 10;
res = (ns % 10) + res;
if (k == n2len - 1 && carry > 0)
{
res = carry.ToString() + res;
}
}
var mulres = new ALong(res);
mulres.MulBase(i);
result += mulres;
}
if (num1.IsNegative != num2.IsNegative) { result.SetNegative(true); }
return result;
}
