127 SUBROUTINE csytrs2( UPLO, N, NRHS, A, LDA, IPIV, B, LDB,
137 INTEGER INFO, LDA, LDB, N, NRHS
141 COMPLEX A( lda, * ), B( ldb, * ), WORK( * )
148 parameter( one = (1.0e+0,0.0e+0) )
152 INTEGER I, IINFO, J, K, KP
153 COMPLEX 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(
'CSYTRS2', -info )
187 IF( n.EQ.0 .OR. nrhs.EQ.0 )
192 CALL csyconv( uplo,
'C', n, a, lda, ipiv, work, iinfo )
200 DO WHILE ( k .GE. 1 )
201 IF( ipiv( k ).GT.0 )
THEN
206 $
CALL cswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
212 IF( kp.EQ.-ipiv( k-1 ) )
213 $
CALL cswap( nrhs, b( k-1, 1 ), ldb, b( kp, 1 ), ldb )
220 CALL ctrsm(
'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 cscal( 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 ctrsm(
'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 cswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
265 IF( k .LT. n .AND. kp.EQ.-ipiv( k+1 ) )
266 $
CALL cswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
277 DO WHILE ( k .LE. n )
278 IF( ipiv( k ).GT.0 )
THEN
283 $
CALL cswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
289 IF( kp.EQ.-ipiv( k ) )
290 $
CALL cswap( nrhs, b( k+1, 1 ), ldb, b( kp, 1 ), ldb )
297 CALL ctrsm(
'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 cscal( 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 ctrsm(
'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 cswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
340 IF( k.GT.1 .AND. kp.EQ.-ipiv( k-1 ) )
341 $
CALL cswap( nrhs, b( k, 1 ), ldb, b( kp, 1 ), ldb )
350 CALL csyconv( uplo,
'R', n, a, lda, ipiv, work, iinfo )
subroutine ctrsm(SIDE, UPLO, TRANSA, DIAG, M, N, ALPHA, A, LDA, B, LDB)
CTRSM
subroutine cscal(N, CA, CX, INCX)
CSCAL
subroutine csyconv(UPLO, WAY, N, A, LDA, IPIV, WORK, INFO)
CSYCONV
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine csytrs2(UPLO, N, NRHS, A, LDA, IPIV, B, LDB, WORK, INFO)
CSYTRS2
subroutine cswap(N, CX, INCX, CY, INCY)
CSWAP