/// <summary>
/// Solves A*X=B for X using QR factorization of A.
/// </summary>
/// <param name="a">The A matrix.</param>
/// <param name="rows">The number of rows in the A matrix.</param>
/// <param name="columns">The number of columns in the A matrix.</param>
/// <param name="b">The B matrix.</param>
/// <param name="columnsB">The number of columns of B.</param>
/// <param name="x">On exit, the solution matrix.</param>
/// <param name="work">The work array. The array must have a length of at least N,
/// but should be N*blocksize. The blocksize is machine dependent. On exit, work[0] contains the optimal
/// work size value.</param>
/// <remarks>Rows must be greater or equal to columns.</remarks>
public override void QRSolve(double[] a, int rows, int columns, double[] b, int columnsB, double[] x, double[] work)
{
if (a == null)
{
throw new ArgumentNullException("a");
}
if (b == null)
{
throw new ArgumentNullException("b");
}
if (x == null)
{
throw new ArgumentNullException("x");
}
if (work == null)
{
throw new ArgumentNullException("work");
}
if (a.Length != rows * columns)
{
throw new ArgumentException(Resources.ArgumentArraysSameLength, "a");
}
if (b.Length != rows * columnsB)
{
throw new ArgumentException(Resources.ArgumentArraysSameLength, "b");
}
if (x.Length != columns * columnsB)
{
throw new ArgumentException(Resources.ArgumentArraysSameLength, "x");
}
if (rows < columns)
{
throw new ArgumentException(Resources.RowsLessThanColumns);
}
if (work.Length < 1)
{
work[0] = rows * Control.BlockSize;
throw new ArgumentException(Resources.WorkArrayTooSmall, "work");
}
SafeNativeMethods.d_qr_solve(rows, columns, columnsB, a, b, x, work, work.Length);
}