Provided by: liblapack-doc_3.3.1-1_all

#### NAME

```       LAPACK-3 - solves a triangular system of the form   A * X = B or A**T * X = B,

```

#### SYNOPSIS

```       SUBROUTINE STPTRS( UPLO, TRANS, DIAG, N, NRHS, AP, B, LDB, INFO )

CHARACTER      DIAG, TRANS, UPLO

INTEGER        INFO, LDB, N, NRHS

REAL           AP( * ), B( LDB, * )

```

#### PURPOSE

```       STPTRS solves a triangular system of the form
where A is a triangular matrix of order N stored in packed format,
and B is an N-by-NRHS matrix.  A check is made to verify that A is
nonsingular.

```

#### ARGUMENTS

```        UPLO    (input) CHARACTER*1
= 'U':  A is upper triangular;
= 'L':  A is lower triangular.

TRANS   (input) CHARACTER*1
Specifies the form of the system of equations:
= 'N':  A * X = B  (No transpose)
= 'T':  A**T * X = B  (Transpose)
= 'C':  A**H * X = B  (Conjugate transpose = Transpose)

DIAG    (input) CHARACTER*1
= 'N':  A is non-unit triangular;
= 'U':  A is unit triangular.

N       (input) INTEGER
The order of the matrix A.  N >= 0.

NRHS    (input) INTEGER
The number of right hand sides, i.e., the number of columns
of the matrix B.  NRHS >= 0.

AP      (input) REAL array, dimension (N*(N+1)/2)
The upper or lower triangular matrix A, packed columnwise in
a linear array.  The j-th column of A is stored in the array
AP as follows:
if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2*n-j)/2) = A(i,j) for j<=i<=n.

B       (input/output) REAL array, dimension (LDB,NRHS)
On entry, the right hand side matrix B.
On exit, if INFO = 0, the solution matrix X.

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

INFO    (output) INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value
> 0:  if INFO = i, the i-th diagonal element of A is zero,
indicating that the matrix is singular and the
solutions X have not been computed.

LAPACK routine (version 3.2)               April 2011                            STPTRS(3lapack)
```