# zptts2.f - Man Page

SRC/zptts2.f

## Synopsis

### Functions/Subroutines

subroutine **zptts2** (iuplo, n, nrhs, d, e, b, ldb)**ZPTTS2** solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.

## Function/Subroutine Documentation

### subroutine zptts2 (integer iuplo, integer n, integer nrhs, double precision, dimension( * ) d, complex*16, dimension( * ) e, complex*16, dimension( ldb, * ) b, integer ldb)

**ZPTTS2** solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.

**Purpose:**

ZPTTS2 solves a tridiagonal system of the form A * X = B using the factorization A = U**H *D*U or A = L*D*L**H computed by ZPTTRF. D is a diagonal matrix specified in the vector D, U (or L) is a unit bidiagonal matrix whose superdiagonal (subdiagonal) is specified in the vector E, and X and B are N by NRHS matrices.

**Parameters***IUPLO*IUPLO is INTEGER Specifies the form of the factorization and whether the vector E is the superdiagonal of the upper bidiagonal factor U or the subdiagonal of the lower bidiagonal factor L. = 1: A = U**H *D*U, E is the superdiagonal of U = 0: A = L*D*L**H, E is the subdiagonal of L

*N*N is INTEGER The order of the tridiagonal matrix A. N >= 0.

*NRHS*NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.

*D*D is DOUBLE PRECISION array, dimension (N) The n diagonal elements of the diagonal matrix D from the factorization A = U**H *D*U or A = L*D*L**H.

*E*E is COMPLEX*16 array, dimension (N-1) If IUPLO = 1, the (n-1) superdiagonal elements of the unit bidiagonal factor U from the factorization A = U**H*D*U. If IUPLO = 0, the (n-1) subdiagonal elements of the unit bidiagonal factor L from the factorization A = L*D*L**H.

*B*B is COMPLEX*16 array, dimension (LDB,NRHS) On entry, the right hand side vectors B for the system of linear equations. On exit, the solution vectors, X.

*LDB*LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N).

**Author**Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **112** of file **zptts2.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page zptts2(3) is an alias of zptts2.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK