146 SUBROUTINE sgbtf2( M, N, KL, KU, AB, LDAB, IPIV, INFO )
154 INTEGER INFO, KL, KU, LDAB, M, N
165 parameter ( one = 1.0e+0, zero = 0.0e+0 )
168 INTEGER I, J, JP, JU, KM, KV
192 ELSE IF( n.LT.0 )
THEN
194 ELSE IF( kl.LT.0 )
THEN
196 ELSE IF( ku.LT.0 )
THEN
198 ELSE IF( ldab.LT.kl+kv+1 )
THEN
202 CALL xerbla(
'SGBTF2', -info )
208 IF( m.EQ.0 .OR. n.EQ.0 )
215 DO 20 j = ku + 2, min( kv, n )
216 DO 10 i = kv - j + 2, kl
226 DO 40 j = 1, min( m, n )
240 jp = isamax( km+1, ab( kv+1, j ), 1 )
241 ipiv( j ) = jp + j - 1
242 IF( ab( kv+jp, j ).NE.zero )
THEN
243 ju = max( ju, min( j+ku+jp-1, n ) )
248 $
CALL sswap( ju-j+1, ab( kv+jp, j ), ldab-1,
249 $ ab( kv+1, j ), ldab-1 )
255 CALL sscal( km, one / ab( kv+1, j ), ab( kv+2, j ), 1 )
260 $
CALL sger( km, ju-j, -one, ab( kv+2, j ), 1,
261 $ ab( kv, j+1 ), ldab-1, ab( kv+1, j+1 ),
subroutine sger(M, N, ALPHA, X, INCX, Y, INCY, A, LDA)
SGER
subroutine sgbtf2(M, N, KL, KU, AB, LDAB, IPIV, INFO)
SGBTF2 computes the LU factorization of a general band matrix using the unblocked version of the algo...
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine sscal(N, SA, SX, INCX)
SSCAL
subroutine sswap(N, SX, INCX, SY, INCY)
SSWAP