public long GetFabonacciNumber(int n)
{
if (n <= 0)
{
throw new ArgumentOutOfRangeException("n");
}
if (n == 1)
{
return(m_FirstNumber);
}
if (n == 2)
{
return(m_SecondNumber);
}
n -= 2;
MatrixFibonacci result = new MatrixFibonacci(1, 0, 0, 1);
MatrixFibonacci temp = new MatrixFibonacci(1, 1, 1, 0);
while (n != 0)
{
if ((n & 1) == 1)
{
result.Multiply(temp);
}
temp.Multiply(temp);
n >>= 1;
}
return(result[0] * m_SecondNumber + result[1] * m_FirstNumber);
}
public void Multiply(MatrixFibonacci matrix)
{
var v11 = m_v11 * matrix.m_v11 + m_v12 * matrix.m_v21;
var v12 = m_v11 * matrix.m_v12 + m_v12 * matrix.m_v22;
var v21 = m_v21 * matrix.m_v11 + m_v22 * matrix.m_v21;
var v22 = m_v21 * matrix.m_v12 + m_v22 * matrix.m_v22;
m_v11 = v11;
m_v12 = v12;
m_v21 = v21;
m_v22 = v22;
}
