LAPACK 3.12.0
LAPACK: Linear Algebra PACKage
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◆ dptsv()

subroutine dptsv ( integer  n,
integer  nrhs,
double precision, dimension( * )  d,
double precision, dimension( * )  e,
double precision, dimension( ldb, * )  b,
integer  ldb,
integer  info 
)

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

Download DPTSV + dependencies [TGZ] [ZIP] [TXT]

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

 A is factored as A = L*D*L**T, 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**T.
[in,out]E
          E is DOUBLE PRECISION 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**T factorization of
          A.  (E can also be regarded as the superdiagonal of the unit
          bidiagonal factor U from the U**T*D*U factorization of A.)
[in,out]B
          B is DOUBLE PRECISION 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 principal minor of order i
                is not positive, and the solution has not been
                computed.  The factorization has not been completed
                unless i = N.
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.