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NAME
     spbtrs - solve 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

SYNOPSIS
     SUBROUTINE SPBTRS( UPLO, N, KD, NRHS, AB, LDAB, B, LDB, INFO
               )

     CHARACTER UPLO

     INTEGER INFO, KD, LDAB, LDB, N, NRHS

     REAL AB( LDAB, * ), B( LDB, * )



     #include <sunperf.h>

     void spbtrs(char uplo, int n, int kd, int nrhs, float  *sab,
               int ldab, float *sb, int ldb, int *info) ;

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.


ARGUMENTS
     UPLO      (input) CHARACTER*1
               = 'U':  Upper triangular factor stored in AB;
               = 'L':  Lower triangular factor stored in AB.

     N         (input) INTEGER
               The order of the matrix A.  N >= 0.

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

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

     AB        (input) 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      (input) INTEGER
               The leading dimension of the array  AB.   LDAB  >=
               KD+1.

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

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

     INFO      (output) INTEGER
               = 0:  successful exit
               < 0:  if INFO = -i, the i-th argument had an ille-
               gal value

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