.TH DTPTRS 1 "November 2006" " LAPACK routine (version 3.1) " " LAPACK routine (version 3.1) "
.SH NAME
DTPTRS - a triangular system of the form A * X = B or A**T * X = B,
.SH SYNOPSIS
.TP 19
SUBROUTINE DTPTRS(
UPLO, TRANS, DIAG, N, NRHS, AP, B, LDB, INFO )
.TP 19
.ti +4
CHARACTER
DIAG, TRANS, UPLO
.TP 19
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INTEGER
INFO, LDB, N, NRHS
.TP 19
.ti +4
DOUBLE
PRECISION AP( * ), B( LDB, * )
.SH 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 N-by-NRHS matrix. A check is made to verify that A is
nonsingular.
.br
.SH ARGUMENTS
.TP 8
UPLO (input) CHARACTER*1
= \(aqU\(aq: A is upper triangular;
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= \(aqL\(aq: A is lower triangular.
.TP 8
TRANS (input) CHARACTER*1
.br
Specifies the form of the system of equations:
.br
= \(aqN\(aq: A * X = B (No transpose)
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= \(aqT\(aq: A**T * X = B (Transpose)
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= \(aqC\(aq: A**H * X = B (Conjugate transpose = Transpose)
.TP 8
DIAG (input) CHARACTER*1
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= \(aqN\(aq: A is non-unit triangular;
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= \(aqU\(aq: A is unit triangular.
.TP 8
N (input) INTEGER
The order of the matrix A. N >= 0.
.TP 8
NRHS (input) INTEGER
The number of right hand sides, i.e., the number of columns
of the matrix B. NRHS >= 0.
.TP 8
AP (input) DOUBLE PRECISION 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 = \(aqU\(aq, AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = \(aqL\(aq, AP(i + (j-1)*(2*n-j)/2) = A(i,j) for j<=i<=n.
.TP 8
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.
.TP 8
LDB (input) INTEGER
The leading dimension of the array B. LDB >= max(1,N).
.TP 8
INFO (output) INTEGER
= 0: successful exit
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< 0: if INFO = -i, the i-th argument had an illegal value
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> 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.