DPBTRS 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 DPBTRF.

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 DOUBLE PRECISION 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 DOUBLE PRECISION 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

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

November 2011