108 SUBROUTINE strtri( UPLO, DIAG, N, A, LDA, INFO )
126 parameter( one = 1.0e+0, zero = 0.0e+0 )
129 LOGICAL NOUNIT, UPPER
130 INTEGER J, JB, NB, NN
135 EXTERNAL lsame, ilaenv
148 upper = lsame( uplo,
'U' )
149 nounit = lsame( diag,
'N' )
150 IF( .NOT.upper .AND. .NOT.lsame( uplo,
'L' ) )
THEN
152 ELSE IF( .NOT.nounit .AND. .NOT.lsame( diag,
'U' ) )
THEN
154 ELSE IF( n.LT.0 )
THEN
156 ELSE IF( lda.LT.max( 1, n ) )
THEN
160 CALL xerbla(
'STRTRI', -info )
173 IF( a( info, info ).EQ.zero )
181 nb = ilaenv( 1,
'STRTRI', uplo // diag, n, -1, -1, -1 )
182 IF( nb.LE.1 .OR. nb.GE.n )
THEN
186 CALL strti2( uplo, diag, n, a, lda, info )
196 jb = min( nb, n-j+1 )
200 CALL strmm(
'Left',
'Upper',
'No transpose', diag, j-1,
201 $ jb, one, a, lda, a( 1, j ), lda )
202 CALL strsm(
'Right',
'Upper',
'No transpose', diag, j-1,
203 $ jb, -one, a( j, j ), lda, a( 1, j ), lda )
207 CALL strti2(
'Upper', diag, jb, a( j, j ), lda, info )
213 nn = ( ( n-1 ) / nb )*nb + 1
215 jb = min( nb, n-j+1 )
220 CALL strmm(
'Left',
'Lower',
'No transpose', diag,
221 $ n-j-jb+1, jb, one, a( j+jb, j+jb ), lda,
222 $ a( j+jb, j ), lda )
223 CALL strsm(
'Right',
'Lower',
'No transpose', diag,
224 $ n-j-jb+1, jb, -one, a( j, j ), lda,
225 $ a( j+jb, j ), lda )
230 CALL strti2(
'Lower', diag, jb, a( j, j ), lda, info )
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine strtri(UPLO, DIAG, N, A, LDA, INFO)
STRTRI
subroutine strti2(UPLO, DIAG, N, A, LDA, INFO)
STRTI2 computes the inverse of a triangular matrix (unblocked algorithm).
subroutine strmm(SIDE, UPLO, TRANSA, DIAG, M, N, ALPHA, A, LDA, B, LDB)
STRMM
subroutine strsm(SIDE, UPLO, TRANSA, DIAG, M, N, ALPHA, A, LDA, B, LDB)
STRSM