146 INTEGER INFO, LDA, LDB, N, NRHS
150 REAL A( lda, * ), B( ldb, * )
157 parameter( one = 1.0e+0 )
162 REAL AK, AKM1, AKM1K, BK, BKM1, DENOM
177 upper = lsame( uplo,
'U' )
178 IF( .NOT.upper .AND. .NOT.lsame( uplo,
'L' ) )
THEN
180 ELSE IF( n.LT.0 )
THEN
182 ELSE IF( nrhs.LT.0 )
THEN
184 ELSE IF( lda.LT.max( 1, n ) )
THEN
186 ELSE IF( ldb.LT.max( 1, n ) )
THEN
190 CALL
xerbla(
'SSYTRS_ROOK', -info )
196 IF( n.EQ.0 .OR. nrhs.EQ.0 )
216 IF( ipiv( k ).GT.0 )
THEN
224 $ CALL
sswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
229 CALL
sger( k-1, nrhs, -one, a( 1, k ), 1, b( k, 1 ), ldb,
234 CALL
sscal( nrhs, one / a( k, k ), b( k, 1 ), ldb )
244 $ CALL
sswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
248 $ CALL
sswap( nrhs, b( k-1, 1 ), ldb, b( kp, 1 ), ldb )
254 CALL
sger( k-2, nrhs, -one, a( 1, k ), 1, b( k, 1 ),
255 $ ldb, b( 1, 1 ), ldb )
256 CALL
sger( k-2, nrhs, -one, a( 1, k-1 ), 1, b( k-1, 1 ),
257 $ ldb, b( 1, 1 ), ldb )
263 akm1 = a( k-1, k-1 ) / akm1k
264 ak = a( k, k ) / akm1k
265 denom = akm1*ak - one
267 bkm1 = b( k-1, j ) / akm1k
268 bk = b( k, j ) / akm1k
269 b( k-1, j ) = ( ak*bkm1-bk ) / denom
270 b( k, j ) = ( akm1*bk-bkm1 ) / denom
291 IF( ipiv( k ).GT.0 )
THEN
299 $ CALL
sgemv(
'Transpose', k-1, nrhs, -one, b,
300 $ ldb, a( 1, k ), 1, one, b( k, 1 ), ldb )
306 $ CALL
sswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
316 CALL
sgemv(
'Transpose', k-1, nrhs, -one, b,
317 $ ldb, a( 1, k ), 1, one, b( k, 1 ), ldb )
318 CALL
sgemv(
'Transpose', k-1, nrhs, -one, b,
319 $ ldb, a( 1, k+1 ), 1, one, b( k+1, 1 ), ldb )
326 $ CALL
sswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
330 $ CALL
sswap( nrhs, b( k+1, 1 ), ldb, b( kp, 1 ), ldb )
355 IF( ipiv( k ).GT.0 )
THEN
363 $ CALL
sswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
369 $ CALL
sger( n-k, nrhs, -one, a( k+1, k ), 1, b( k, 1 ),
370 $ ldb, b( k+1, 1 ), ldb )
374 CALL
sscal( nrhs, one / a( k, k ), b( k, 1 ), ldb )
384 $ CALL
sswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
388 $ CALL
sswap( nrhs, b( k+1, 1 ), ldb, b( kp, 1 ), ldb )
394 CALL
sger( n-k-1, nrhs, -one, a( k+2, k ), 1, b( k, 1 ),
395 $ ldb, b( k+2, 1 ), ldb )
396 CALL
sger( n-k-1, nrhs, -one, a( k+2, k+1 ), 1,
397 $ b( k+1, 1 ), ldb, b( k+2, 1 ), ldb )
403 akm1 = a( k, k ) / akm1k
404 ak = a( k+1, k+1 ) / akm1k
405 denom = akm1*ak - one
407 bkm1 = b( k, j ) / akm1k
408 bk = b( k+1, j ) / akm1k
409 b( k, j ) = ( ak*bkm1-bk ) / denom
410 b( k+1, j ) = ( akm1*bk-bkm1 ) / denom
431 IF( ipiv( k ).GT.0 )
THEN
439 $ CALL
sgemv(
'Transpose', n-k, nrhs, -one, b( k+1, 1 ),
440 $ ldb, a( k+1, k ), 1, one, b( k, 1 ), ldb )
446 $ CALL
sswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
456 CALL
sgemv(
'Transpose', n-k, nrhs, -one, b( k+1, 1 ),
457 $ ldb, a( k+1, k ), 1, one, b( k, 1 ), ldb )
458 CALL
sgemv(
'Transpose', n-k, nrhs, -one, b( k+1, 1 ),
459 $ ldb, a( k+1, k-1 ), 1, one, b( k-1, 1 ),
467 $ CALL
sswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
471 $ CALL
sswap( nrhs, b( k-1, 1 ), ldb, b( kp, 1 ), ldb )
subroutine ssytrs_rook(UPLO, N, NRHS, A, LDA, IPIV, B, LDB, INFO)
SSYTRS_ROOK
subroutine sswap(N, SX, INCX, SY, INCY)
SSWAP
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine sgemv(TRANS, M, N, ALPHA, A, LDA, X, INCX, BETA, Y, INCY)
SGEMV
subroutine sger(M, N, ALPHA, X, INCX, Y, INCY, A, LDA)
SGER
subroutine sscal(N, SA, SX, INCX)
SSCAL