NAME

SYNOPSIS

  SUBROUTINE SSBMV( UPLO, N, NDIAG, ALPHA, A, LDA, X, INCX, BETA, Y, 
 *      INCY)
  CHARACTER * 1 UPLO
  INTEGER N, NDIAG, LDA, INCX, INCY
  REAL ALPHA, BETA
  REAL A(LDA,*), X(*), Y(*)
 
  SUBROUTINE SSBMV_64( UPLO, N, NDIAG, ALPHA, A, LDA, X, INCX, BETA, 
 *      Y, INCY)
  CHARACTER * 1 UPLO
  INTEGER*8 N, NDIAG, LDA, INCX, INCY
  REAL ALPHA, BETA
  REAL A(LDA,*), X(*), Y(*)
 

F95 INTERFACE

  SUBROUTINE SBMV( UPLO, [N], NDIAG, ALPHA, A, [LDA], X, [INCX], BETA, 
 *       Y, [INCY])
  CHARACTER(LEN=1) :: UPLO
  INTEGER :: N, NDIAG, LDA, INCX, INCY
  REAL :: ALPHA, BETA
  REAL, DIMENSION(:) :: X, Y
  REAL, DIMENSION(:,:) :: A
 
  SUBROUTINE SBMV_64( UPLO, [N], NDIAG, ALPHA, A, [LDA], X, [INCX], 
 *       BETA, Y, [INCY])
  CHARACTER(LEN=1) :: UPLO
  INTEGER(8) :: N, NDIAG, LDA, INCX, INCY
  REAL :: ALPHA, BETA
  REAL, DIMENSION(:) :: X, Y
  REAL, DIMENSION(:,:) :: A
 

C INTERFACE

void ssbmv(char uplo, int n, int ndiag, float alpha, float *a, int lda, float *x, int incx, float beta, float *y, int incy);

void ssbmv_64(char uplo, long n, long ndiag, float alpha, float *a, long lda, float *x, long incx, float beta, float *y, long incy);

PURPOSE

ARGUMENTS

* UPLO (input)

On entry, UPLO specifies whether the upper or lower triangular part of the band matrix A is being supplied as follows:

UPLO = 'U' or 'u' The upper triangular part of A is being supplied.

UPLO = 'L' or 'l' The lower triangular part of A is being supplied.

Unchanged on exit.

* N (input)

On entry, N specifies the order of the matrix A. N >= 0. Unchanged on exit.

* NDIAG (input)

On entry, NDIAG specifies the number of super-diagonals of the matrix A. NDIAG >= 0. Unchanged on exit.

* ALPHA (input)

On entry, ALPHA specifies the scalar alpha. Unchanged on exit.

* A (input)

Before entry with UPLO = 'U' or 'u', the leading ( k + 1 ) by n part of the array A must contain the upper triangular band part of the symmetric matrix, supplied column by column, with the leading diagonal of the matrix in row ( k + 1 ) of the array, the first super-diagonal starting at position 2 in row k, and so on. The top left k by k triangle of the array A is not referenced. The following program segment will transfer the upper triangular part of a symmetric band matrix from conventional full matrix storage to band storage:

   DO 20, J = 1, N
 = NDIAG + 1 - J
O 10, I = MAX( 1, J - NDIAG ), J
       A( M + I, J ) = matrix( I, J )

10 CONTINUE

20 CONTINUE

Before entry with UPLO = 'L' or 'l', the leading ( k + 1 ) by n part of the array A must contain the lower triangular band part of the symmetric matrix, supplied column by column, with the leading diagonal of the matrix in row 1 of the array, the first sub-diagonal starting at position 1 in row 2, and so on. The bottom right k by k triangle of the array A is not referenced. The following program segment will transfer the lower triangular part of a symmetric band matrix from conventional full matrix storage to band storage:

   DO 20, J = 1, N
 = 1 - J
O 10, I = J, MIN( N, J + NDIAG )
       A( M + I, J ) = matrix( I, J )

10 CONTINUE

20 CONTINUE

Unchanged on exit.

* LDA (input)

On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. LDA >= ( k + 1 ). Unchanged on exit.

* X (input)

( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented array X must contain the vector x. Unchanged on exit.

* INCX (input)

On entry, INCX specifies the increment for the elements of X. INCX <> 0. Unchanged on exit.

* BETA (input)

On entry, BETA specifies the scalar beta. Unchanged on exit.

* Y (input/output)

( 1 + ( n - 1 )*abs( INCY ) ). Before entry, the incremented array Y must contain the vector y. On exit, Y is overwritten by the updated vector y.

* INCY (input)

On entry, INCY specifies the increment for the elements of Y. INCY <> 0. Unchanged on exit.