Computes the solution of \(R'x = b\) where R is an upper triangular matrix.
b (PxL matrix) – data
R (PxP matrix) – upper triangular matrix
x (PxL matrix) – solution of \(R'x = b\) where R is an upper triangular matrix
qrtsol() applies a forward solve to \(R'x = b\) to solve for x. Generally R
will be the R matrix from a QR factorization.
qrtsol() may be used,
however, in any situation where R is upper triangular. If R is lower
triangular, transpose before calling
If R is not transposed, use