115 RECURSIVE SUBROUTINE sgelqt3( M, N, A, LDA, T, LDT, INFO )
123 INTEGER INFO, LDA, M, N, LDT
126 REAL A( lda, * ), T( ldt, * )
133 parameter( one = 1.0d+00 )
136 INTEGER I, I1, J, J1, M1, M2, N1, N2, IINFO
146 ELSE IF( n .LT. m )
THEN
148 ELSE IF( lda .LT. max( 1, m ) )
THEN
150 ELSE IF( ldt .LT. max( 1, m ) )
THEN
154 CALL xerbla(
'SGELQT3', -info )
162 CALL slarfg( n, a, a( 1, min( 2, n ) ), lda, t )
175 CALL sgelqt3( m1, n, a, lda, t, ldt, iinfo )
181 t( i+m1, j ) = a( i+m1, j )
184 CALL strmm(
'R',
'U',
'T',
'U', m2, m1, one,
185 & a, lda, t( i1, 1 ), ldt )
187 CALL sgemm(
'N',
'T', m2, m1, n-m1, one, a( i1, i1 ), lda,
188 & a( 1, i1 ), lda, one, t( i1, 1 ), ldt)
190 CALL strmm(
'R',
'U',
'N',
'N', m2, m1, one,
191 & t, ldt, t( i1, 1 ), ldt )
193 CALL sgemm(
'N',
'N', m2, n-m1, m1, -one, t( i1, 1 ), ldt,
194 & a( 1, i1 ), lda, one, a( i1, i1 ), lda )
196 CALL strmm(
'R',
'U',
'N',
'U', m2, m1 , one,
197 & a, lda, t( i1, 1 ), ldt )
201 a( i+m1, j ) = a( i+m1, j ) - t( i+m1, j )
208 CALL sgelqt3( m2, n-m1, a( i1, i1 ), lda,
209 & t( i1, i1 ), ldt, iinfo )
215 t( j, i+m1 ) = (a( j, i+m1 ))
219 CALL strmm(
'R',
'U',
'T',
'U', m1, m2, one,
220 & a( i1, i1 ), lda, t( 1, i1 ), ldt )
222 CALL sgemm(
'N',
'T', m1, m2, n-m, one, a( 1, j1 ), lda,
223 & a( i1, j1 ), lda, one, t( 1, i1 ), ldt )
225 CALL strmm(
'L',
'U',
'N',
'N', m1, m2, -one, t, ldt,
228 CALL strmm(
'R',
'U',
'N',
'N', m1, m2, one,
229 & t( i1, i1 ), ldt, t( 1, i1 ), ldt )
subroutine dtrmm(SIDE, UPLO, TRANSA, DIAG, M, N, ALPHA, A, LDA, B, LDB)
DTRMM
subroutine sgemm(TRANSA, TRANSB, M, N, K, ALPHA, A, LDA, B, LDB, BETA, C, LDC)
SGEMM
subroutine dgemm(TRANSA, TRANSB, M, N, K, ALPHA, A, LDA, B, LDB, BETA, C, LDC)
DGEMM
recursive subroutine sgelqt3(M, N, A, LDA, T, LDT, INFO)
subroutine strmm(SIDE, UPLO, TRANSA, DIAG, M, N, ALPHA, A, LDA, B, LDB)
STRMM
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine dlarfg(N, ALPHA, X, INCX, TAU)
DLARFG generates an elementary reflector (Householder matrix).
subroutine slarfg(N, ALPHA, X, INCX, TAU)
SLARFG generates an elementary reflector (Householder matrix).