LAPACK  3.6.1 LAPACK: Linear Algebra PACKage
 subroutine zptsv ( integer N, integer NRHS, double precision, dimension( * ) D, complex*16, dimension( * ) E, complex*16, dimension( ldb, * ) B, integer LDB, integer INFO )

ZPTSV computes the solution to system of linear equations A * X = B for PT matrices

Purpose:
``` ZPTSV computes the solution to a complex system of linear equations
A*X = B, where A is an N-by-N Hermitian positive definite tridiagonal
matrix, and X and B are N-by-NRHS matrices.

A is factored as A = L*D*L**H, and the factored form of A is then
used to solve the system of equations.```
Parameters
 [in] N ``` N is INTEGER The order of the matrix A. N >= 0.``` [in] NRHS ``` NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.``` [in,out] D ``` D is DOUBLE PRECISION array, dimension (N) On entry, the n diagonal elements of the tridiagonal matrix A. On exit, the n diagonal elements of the diagonal matrix D from the factorization A = L*D*L**H.``` [in,out] E ``` E is COMPLEX*16 array, dimension (N-1) On entry, the (n-1) subdiagonal elements of the tridiagonal matrix A. On exit, the (n-1) subdiagonal elements of the unit bidiagonal factor L from the L*D*L**H factorization of A. E can also be regarded as the superdiagonal of the unit bidiagonal factor U from the U**H*D*U factorization of A.``` [in,out] B ``` B is COMPLEX*16 array, dimension (LDB,NRHS) On entry, the N-by-NRHS right hand side matrix B. On exit, if INFO = 0, the N-by-NRHS solution matrix X.``` [in] LDB ``` LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N).``` [out] INFO ``` INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i, the leading minor of order i is not positive definite, and the solution has not been computed. The factorization has not been completed unless i = N.```
Date
September 2012

Definition at line 117 of file zptsv.f.

117 *
118 * -- LAPACK driver routine (version 3.4.2) --
119 * -- LAPACK is a software package provided by Univ. of Tennessee, --
120 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
121 * September 2012
122 *
123 * .. Scalar Arguments ..
124  INTEGER info, ldb, n, nrhs
125 * ..
126 * .. Array Arguments ..
127  DOUBLE PRECISION d( * )
128  COMPLEX*16 b( ldb, * ), e( * )
129 * ..
130 *
131 * =====================================================================
132 *
133 * .. External Subroutines ..
134  EXTERNAL xerbla, zpttrf, zpttrs
135 * ..
136 * .. Intrinsic Functions ..
137  INTRINSIC max
138 * ..
139 * .. Executable Statements ..
140 *
141 * Test the input parameters.
142 *
143  info = 0
144  IF( n.LT.0 ) THEN
145  info = -1
146  ELSE IF( nrhs.LT.0 ) THEN
147  info = -2
148  ELSE IF( ldb.LT.max( 1, n ) ) THEN
149  info = -6
150  END IF
151  IF( info.NE.0 ) THEN
152  CALL xerbla( 'ZPTSV ', -info )
153  RETURN
154  END IF
155 *
156 * Compute the L*D*L**H (or U**H*D*U) factorization of A.
157 *
158  CALL zpttrf( n, d, e, info )
159  IF( info.EQ.0 ) THEN
160 *
161 * Solve the system A*X = B, overwriting B with X.
162 *
163  CALL zpttrs( 'Lower', n, nrhs, d, e, b, ldb, info )
164  END IF
165  RETURN
166 *
167 * End of ZPTSV
168 *
subroutine zpttrs(UPLO, N, NRHS, D, E, B, LDB, INFO)
ZPTTRS
Definition: zpttrs.f:123
subroutine zpttrf(N, D, E, INFO)
ZPTTRF
Definition: zpttrf.f:94
subroutine xerbla(SRNAME, INFO)
XERBLA
Definition: xerbla.f:62

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