
STPTRS(l) ) STPTRS(l)
NAME
STPTRS  solve 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 A * X = B or A**T * X = B, where A is a tri
angular matrix of order N stored in packed format, and B is an NbyNRHS 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 nonunit 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
jth column of A is stored in the array AP as follows: if UPLO = 'U', AP(i +
(j1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j1)*(2*nj)/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 ith argument had an illegal value
> 0: if INFO = i, the ith diagonal element of A is zero, indicating that the
matrix is singular and the solutions X have not been computed.
LAPACK version 3.0 15 June 2000 STPTRS(l) 
