zpttrs.f - Man Page



subroutine zpttrs (UPLO, N, NRHS, D, E, B, LDB, INFO)

Function/Subroutine Documentation

subroutine zpttrs (character UPLO, integer N, integer NRHS, double precision, dimension( * ) D, complex*16, dimension( * ) E, complex*16, dimension( ldb, * ) B, integer LDB, integer INFO)



 ZPTTRS solves a tridiagonal system of the form
    A * X = B
 using the factorization A = U**H *D* U or A = L*D*L**H computed by ZPTTRF.
 D is a diagonal matrix specified in the vector D, U (or L) is a unit
 bidiagonal matrix whose superdiagonal (subdiagonal) is specified in
 the vector E, and X and B are N by NRHS matrices.


          UPLO is CHARACTER*1
          Specifies the form of the factorization and whether the
          vector E is the superdiagonal of the upper bidiagonal factor
          U or the subdiagonal of the lower bidiagonal factor L.
          = 'U':  A = U**H *D*U, E is the superdiagonal of U
          = 'L':  A = L*D*L**H, E is the subdiagonal of L


          N is INTEGER
          The order of the tridiagonal matrix A.  N >= 0.


          NRHS is INTEGER
          The number of right hand sides, i.e., the number of columns
          of the matrix B.  NRHS >= 0.


          D is DOUBLE PRECISION array, dimension (N)
          The n diagonal elements of the diagonal matrix D from the
          factorization A = U**H *D*U or A = L*D*L**H.


          E is COMPLEX*16 array, dimension (N-1)
          If UPLO = 'U', the (n-1) superdiagonal elements of the unit
          bidiagonal factor U from the factorization A = U**H*D*U.
          If UPLO = 'L', the (n-1) subdiagonal elements of the unit
          bidiagonal factor L from the factorization A = L*D*L**H.


          B is COMPLEX*16 array, dimension (LDB,NRHS)
          On entry, the right hand side vectors B for the system of
          linear equations.
          On exit, the solution vectors, X.


          LDB is INTEGER
          The leading dimension of the array B.  LDB >= max(1,N).


          INFO is INTEGER
          = 0: successful exit
          < 0: if INFO = -k, the k-th argument had an illegal value

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.


June 2016

Definition at line 123 of file zpttrs.f.


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Referenced By

The man page zpttrs(3) is an alias of zpttrs.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK