dtptrs (l)  Linux Man Pages
dtptrs: solves a triangular system of the form A * X = B or A**T * X = B,
Command to display dtptrs
manual in Linux: $ man l dtptrs
NAME
DTPTRS  solves a triangular system of the form A * X = B or A**T * X = B,
SYNOPSIS
 SUBROUTINE DTPTRS(

UPLO, TRANS, DIAG, N, NRHS, AP, B, LDB, INFO )

CHARACTER
DIAG, TRANS, UPLO

INTEGER
INFO, LDB, N, NRHS

DOUBLE
PRECISION AP( * ), B( LDB, * )
PURPOSE
DTPTRS solves a triangular system of the form
where A is a triangular 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

= aqUaq: A is upper triangular;
= aqLaq: A is lower triangular.
 TRANS (input) CHARACTER*1

Specifies the form of the system of equations:
= aqNaq: A * X = B (No transpose)
= aqTaq: A**T * X = B (Transpose)
= aqCaq: A**H * X = B (Conjugate transpose = Transpose)
 DIAG (input) CHARACTER*1

= aqNaq: A is nonunit triangular;
= aqUaq: 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) DOUBLE PRECISION 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 = aqUaq, AP(i + (j1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = aqLaq, AP(i + (j1)*(2*nj)/2) = A(i,j) for j<=i<=n.
 B (input/output) DOUBLE PRECISION 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.
Pages related to dtptrs
 dtptrs (3)
 dtptri (l)  computes the inverse of a real upper or lower triangular matrix A stored in packed format
 dtpttf (l)  copies a triangular matrix A from standard packed format (TP) to rectangular full packed format (TF)
 dtpttr (l)  copies a triangular matrix A from standard packed format (TP) to standard full format (TR)
 dtpcon (l)  estimates the reciprocal of the condition number of a packed triangular matrix A, in either the 1norm or the infinitynorm
 dtpmv (l)  performs one of the matrixvector operations x := A*x, or x := Aaq*x,
 dtprfs (l)  provides error bounds and backward error estimates for the solution to a system of linear equations with a triangular packed coefficient matrix
 dtpsv (l)  solves one of the systems of equations A*x = b, or Aaq*x = b,