/// <summary>
/// Returns the value contained in a quantum register, with optional portion start and length
/// </summary>
/// <param name="portionStart">The portion start.</param>
/// <param name="portionLength">Length of the portion.</param>
/// <returns></returns>
/// <exception cref="ArgumentException">The supplied portion overflows the given quantum register.</exception>
/// <exception cref="SystemException">A value can only be extracted from a pure state quantum register.</exception>
public int GetValue(int portionStart = 0, int portionLength = 0)
{
int registerLength = QCUtil.Log2((int)this.BitRegister.Size - 1);
if (portionLength == 0)
{
portionLength = registerLength - portionStart;
}
int trailingBitCount = registerLength - portionStart - portionLength;
if (trailingBitCount < 0)
{
throw new ArgumentException("The supplied portion overflows the given quantum register.");
}
int index = -1;
for (int i = 0; i < this.BitRegister.Size; i++)
{
if (this.BitRegister[i].Real == 1)
{
index = i;
break;
}
}
if (index == -1)
{
throw new SystemException("A value can only be extracted from a pure state quantum register.");
}
// If trailing bits need to be removed
if (trailingBitCount > 0)
{
index >>= trailingBitCount;
}
// If leading bits need to be removed
if (portionStart > 0)
{
index &= (1 << portionLength) - 1;
}
return(index);
}
/// <summary>
/// Initializes a new instance of the <see cref="Qubit"/> class. Constructor from Bloch sphere coordinates
/// </summary>
/// <param name="colatitude">The colatitude.</param>
/// <param name="longitude">The longitude.</param>
public Qubit(float colatitude, float longitude)
: this(Math.Cos(colatitude / 2), Math.Sin(colatitude / 2) * QCUtil.ComplexExp(Complex.ImaginaryOne * longitude))
{
}
