/// <summary>
/// arccos(): the inverse function of cos(), input range (0..pi)
/// </summary>
/// <param name="n1">The number to find the arccosine of (0..pi)</param>
/// <remarks>Note that inverse trig functions are only defined within a specific range.
/// Values outside this range will return NaN, although some margin for error is assumed.
/// </remarks>
public static BigFloat Arccos(BigFloat n1)
{
BigFloat res = new BigFloat(n1);
n1.Arccos();
return n1;
}