# dptts2.f man page

dptts2.f —

## Synopsis

### Functions/Subroutines

subroutinedptts2(N, NRHS, D, E, B, LDB)DPTTS2solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.

## Function/Subroutine Documentation

### subroutine dptts2 (integerN, integerNRHS, double precision, dimension( * )D, double precision, dimension( * )E, double precision, dimension( ldb, * )B, integerLDB)

**DPTTS2** solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.

**Purpose:**

```
DPTTS2 solves a tridiagonal system of the form
A * X = B
using the L*D*L**T factorization of A computed by DPTTRF. D is a
diagonal matrix specified in the vector D, L is a unit bidiagonal
matrix whose subdiagonal is specified in the vector E, and X and B
are N by NRHS matrices.
```

**Parameters:**

*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
L*D*L**T factorization of A.
```

*E*

```
E is DOUBLE PRECISION array, dimension (N-1)
The (n-1) subdiagonal elements of the unit bidiagonal factor
L from the L*D*L**T factorization of A. E can also be regarded
as the superdiagonal of the unit bidiagonal factor U from the
factorization A = U**T*D*U.
```

*B*

```
B is DOUBLE PRECISION 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.

**Date:**

September 2012

Definition at line 103 of file dptts2.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

dptts2(3) is an alias of dptts2.f(3).