Purpose
=======
LA_PTSV computes the solution to a linear system of equations
A*X = B, where A has tridiagonal form and is real symmetric or complex
Hermitian and, in either case, positive definite, and where X and B are
rectangular matrices or vectors. A is factored as A = L*D*L^H, where L
is a unit lower bidiagonal matrix and D is a diagonal matrix. The
factored form of A is then used to solve the above system.
=========
SUBROUTINE LA_PTSV( D, E, B, INFO=info )
REAL(), INTENT(INOUT) :: D(:)
(), INTENT(INOUT) :: E(:),
INTEGER, INTENT(OUT), OPTIONAL :: INFO
where
::= REAL | COMPLEX
::= KIND(1.0) | KIND(1.0D0)
::= B(:,:) | B(:)
Arguments
=========
D (input/output) REAL array, shape (:) with size(D) = n, where n
is the order of A.
On entry, the diagonal of A.
On exit, the diagonal of D.
E (input/output) REAL or COMPLEX array, shape (:), with
size(E) = n-1.
On entry, the subdiagonal of A.
On exit, the subdiagonal of L.
B (input/output) REAL or COMPLEX array, shape (:,:) with
size(B,1) = n or shape (:) with size(B) = n.
On entry, the matrix B.
On exit, the solution matrix X.
INFO Optional (output) INTEGER.
= 0: successful exit.
< 0: if INFO = -i, the i-th argument had an illegal value.
> 0: if INFO = i, the leading minor of order i of A is not
positive definite, and the solution has not been computed.
The factorization has not been completed unless i = n.
If INFO is not present and an error occurs, then the program is
terminated with an error message.