127 SUBROUTINE dsytrs2( UPLO, N, NRHS, A, LDA, IPIV, B, LDB,
137 INTEGER INFO, LDA, LDB, N, NRHS
141 DOUBLE PRECISION A( lda, * ), B( ldb, * ), WORK( * )
148 parameter( one = 1.0d+0 )
152 INTEGER I, IINFO, J, K, KP
153 DOUBLE PRECISION AK, AKM1, AKM1K, BK, BKM1, DENOM
168 upper = lsame( uplo,
'U' )
169 IF( .NOT.upper .AND. .NOT.lsame( uplo,
'L' ) )
THEN
171 ELSE IF( n.LT.0 )
THEN
173 ELSE IF( nrhs.LT.0 )
THEN
175 ELSE IF( lda.LT.max( 1, n ) )
THEN
177 ELSE IF( ldb.LT.max( 1, n ) )
THEN
181 CALL
xerbla(
'DSYTRS2', -info )
187 IF( n.EQ.0 .OR. nrhs.EQ.0 )
192 CALL
dsyconv( uplo,
'C', n, a, lda, ipiv, work, iinfo )
200 DO WHILE ( k .GE. 1 )
201 IF( ipiv( k ).GT.0 )
THEN
206 $ CALL
dswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
212 IF( kp.EQ.-ipiv( k-1 ) )
213 $ CALL
dswap( nrhs, b( k-1, 1 ), ldb, b( kp, 1 ), ldb )
220 CALL
dtrsm(
'L',
'U',
'N',
'U',n,nrhs,one,a,lda,b,ldb)
225 DO WHILE ( i .GE. 1 )
226 IF( ipiv(i) .GT. 0 )
THEN
227 CALL
dscal( nrhs, one / a( i, i ), b( i, 1 ), ldb )
228 ELSEIF ( i .GT. 1)
THEN
229 IF ( ipiv(i-1) .EQ. ipiv(i) )
THEN
231 akm1 = a( i-1, i-1 ) / akm1k
232 ak = a( i, i ) / akm1k
233 denom = akm1*ak - one
235 bkm1 = b( i-1, j ) / akm1k
236 bk = b( i, j ) / akm1k
237 b( i-1, j ) = ( ak*bkm1-bk ) / denom
238 b( i, j ) = ( akm1*bk-bkm1 ) / denom
248 CALL
dtrsm(
'L',
'U',
'T',
'U',n,nrhs,one,a,lda,b,ldb)
253 DO WHILE ( k .LE. n )
254 IF( ipiv( k ).GT.0 )
THEN
259 $ CALL
dswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
265 IF( k .LT. n .AND. kp.EQ.-ipiv( k+1 ) )
266 $ CALL
dswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
277 DO WHILE ( k .LE. n )
278 IF( ipiv( k ).GT.0 )
THEN
283 $ CALL
dswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
289 IF( kp.EQ.-ipiv( k ) )
290 $ CALL
dswap( nrhs, b( k+1, 1 ), ldb, b( kp, 1 ), ldb )
297 CALL
dtrsm(
'L',
'L',
'N',
'U',n,nrhs,one,a,lda,b,ldb)
302 DO WHILE ( i .LE. n )
303 IF( ipiv(i) .GT. 0 )
THEN
304 CALL
dscal( nrhs, one / a( i, i ), b( i, 1 ), ldb )
307 akm1 = a( i, i ) / akm1k
308 ak = a( i+1, i+1 ) / akm1k
309 denom = akm1*ak - one
311 bkm1 = b( i, j ) / akm1k
312 bk = b( i+1, j ) / akm1k
313 b( i, j ) = ( ak*bkm1-bk ) / denom
314 b( i+1, j ) = ( akm1*bk-bkm1 ) / denom
323 CALL
dtrsm(
'L',
'L',
'T',
'U',n,nrhs,one,a,lda,b,ldb)
328 DO WHILE ( k .GE. 1 )
329 IF( ipiv( k ).GT.0 )
THEN
334 $ CALL
dswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
340 IF( k.GT.1 .AND. kp.EQ.-ipiv( k-1 ) )
341 $ CALL
dswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
350 CALL
dsyconv( uplo,
'R', n, a, lda, ipiv, work, iinfo )
subroutine dsyconv(UPLO, WAY, N, A, LDA, IPIV, WORK, INFO)
DSYCONV
subroutine dsytrs2(UPLO, N, NRHS, A, LDA, IPIV, B, LDB, WORK, INFO)
DSYTRS2
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine dscal(N, DA, DX, INCX)
DSCAL
subroutine dtrsm(SIDE, UPLO, TRANSA, DIAG, M, N, ALPHA, A, LDA, B, LDB)
DTRSM
subroutine dswap(N, DX, INCX, DY, INCY)
DSWAP