SRC/spbtrs.f(3)

NAME
SRC/spbtrs.f

SYNOPSIS

  Functions/Subroutines
subroutine spbtrs (uplo, n, kd, nrhs, ab, ldab, b, ldb, info)
SPBTRS

Function/Subroutine Documentation

  subroutine spbtrs (character uplo, integer n, integer kd, integer nrhs, real, dimension( ldab, * ) ab, integer ldab, real, dimension( ldb, * ) b, integer ldb, integer info)

SPBTRS

Purpose:

     SPBTRS solves a system of linear equations A*X = B with a symmetric
     positive definite band matrix A using the Cholesky factorization
     A = U**T*U or A = L*L**T computed by SPBTRF.

Parameters
    UPLO

              UPLO is CHARACTER*1
              = 'U':  Upper triangular factor stored in AB;
              = 'L':  Lower triangular factor stored in AB.

    N

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

    KD

              KD is INTEGER
              The number of superdiagonals of the matrix A if UPLO = 'U',
              or the number of subdiagonals if UPLO = 'L'.  KD >= 0.

    NRHS

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

    AB

              AB is REAL array, dimension (LDAB,N)
              The triangular factor U or L from the Cholesky factorization
              A = U**T*U or A = L*L**T of the band matrix A, stored in the
              first KD+1 rows of the array.  The j-th column of U or L is
              stored in the j-th column of the array AB as follows:
              if UPLO ='U', AB(kd+1+i-j,j) = U(i,j) for max(1,j-kd)<=i<=j;
              if UPLO ='L', AB(1+i-j,j)    = L(i,j) for j<=i<=min(n,j+kd).

    LDAB

              LDAB is INTEGER
              The leading dimension of the array AB.  LDAB >= KD+1.

    B

              B is REAL array, dimension (LDB,NRHS)
              On entry, the right hand side matrix B.
              On exit, the solution matrix X.

    LDB

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

    INFO

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

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 120 of file spbtrs.f.

Author

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