Computes all the eigenvalues of the symmetric positive definite tridiagonal matrix associated with the quotient difference array z to high relative accuracy. Used by ?bdsqr and ?stegr.
Reduces the first nb rows and columns of a symmetric/Hermitian matrix A to real tridiagonal form by an orthogonal/unitary similarity transformation.
Solves a tridiagonal system of the form
A*X=B using the
L*D*LH factorization computed by ?pttrf.
Generates a real or complex elementary reflector.
Copies a triangular matrix from the standard full format (TR) to the rectangular full packed format (TF).
Improves the computed solution to a system of linear equations for general matrices by performing extra-precise iterative refinement and provides error bounds and backward error estimates for the solution.
Performs reciprocal diagonal scaling on a vector.
Called from ?lamc2. Determines machine parameters given by beta, t, rnd, ieee1.
The model of the computing environment for ScaLAPACK is represented as a one-dimensional array of processes (for operations on band or tridiagonal matrices) or also a two-dimensional process grid (for operations on dense matrices). To use ScaLAPACK, all global matrices or vectors should be distributed on this array or grid prior to calling the ScaLAPACK routines.
Solves a system of linear equations with a diagonally dominant-like tridiagonal distributed matrix using the factorization computed by p?dttrf.