1 *> \brief \b ZLA_GERCOND_C
3 * =========== DOCUMENTATION ===========
5 * Online html documentation available at
6 * http://www.netlib.org/lapack/explore-html/
11 * DOUBLE PRECISION FUNCTION ZLA_GERCOND_C( TRANS, N, A, LDA, AF,
12 * LDAF, IPIV, C, CAPPLY,
15 * .. Scalar Aguments ..
18 * INTEGER N, LDA, LDAF, INFO
20 * .. Array Arguments ..
22 * COMPLEX*16 A( LDA, * ), AF( LDAF, * ), WORK( * )
23 * DOUBLE PRECISION C( * ), RWORK( * )
29 *>\details \b Purpose:
32 *> ZLA_GERCOND_C computes the infinity norm condition number of
33 *> op(A) * inv(diag(C)) where C is a DOUBLE PRECISION vector.
42 *> TRANS is CHARACTER*1
43 *> Specifies the form of the system of equations:
44 *> = 'N': A * X = B (No transpose)
45 *> = 'T': A**T * X = B (Transpose)
46 *> = 'C': A**H * X = B (Conjugate Transpose = Transpose)
52 *> The number of linear equations, i.e., the order of the
58 *> A is COMPLEX*16 array, dimension (LDA,N)
59 *> On entry, the N-by-N matrix A
65 *> The leading dimension of the array A. LDA >= max(1,N).
70 *> AF is COMPLEX*16 array, dimension (LDAF,N)
71 *> The factors L and U from the factorization
72 *> A = P*L*U as computed by ZGETRF.
78 *> The leading dimension of the array AF. LDAF >= max(1,N).
83 *> IPIV is INTEGER array, dimension (N)
84 *> The pivot indices from the factorization A = P*L*U
85 *> as computed by ZGETRF; row i of the matrix was interchanged
91 *> C is DOUBLE PRECISION array, dimension (N)
92 *> The vector C in the formula op(A) * inv(diag(C)).
98 *> If .TRUE. then access the vector C in the formula above.
104 *> = 0: Successful exit.
105 *> i > 0: The ith argument is invalid.
110 *> WORK is COMPLEX*16 array, dimension (2*N).
116 *> RWORK is DOUBLE PRECISION array, dimension (N).
124 *> \author Univ. of Tennessee
125 *> \author Univ. of California Berkeley
126 *> \author Univ. of Colorado Denver
129 *> \date November 2011
131 *> \ingroup complex16GEcomputational
133 * =====================================================================
134 DOUBLE PRECISION FUNCTION ZLA_GERCOND_C( TRANS, N, A, LDA, AF,
135 $ LDAF, IPIV, C, CAPPLY,
136 $ INFO, WORK, RWORK )
138 * -- LAPACK computational routine (version 3.2.1) --
139 * -- LAPACK is a software package provided by Univ. of Tennessee, --
140 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
143 * .. Scalar Aguments ..
146 INTEGER N, LDA, LDAF, INFO
148 * .. Array Arguments ..
150 COMPLEX*16 A( LDA, * ), AF( LDAF, * ), WORK( * )
151 DOUBLE PRECISION C( * ), RWORK( * )
154 * =====================================================================
156 * .. Local Scalars ..
159 DOUBLE PRECISION AINVNM, ANORM, TMP
165 * .. External Functions ..
169 * .. External Subroutines ..
170 EXTERNAL ZLACN2, ZGETRS, XERBLA
172 * .. Intrinsic Functions ..
173 INTRINSIC ABS, MAX, REAL, DIMAG
175 * .. Statement Functions ..
176 DOUBLE PRECISION CABS1
178 * .. Statement Function Definitions ..
179 CABS1( ZDUM ) = ABS( DBLE( ZDUM ) ) + ABS( DIMAG( ZDUM ) )
181 * .. Executable Statements ..
182 ZLA_GERCOND_C = 0.0D+0
185 NOTRANS = LSAME( TRANS, 'N' )
186 IF ( .NOT. NOTRANS .AND. .NOT. LSAME( TRANS, 'T' ) .AND. .NOT.
187 $ LSAME( TRANS, 'C' ) ) THEN
188 ELSE IF( N.LT.0 ) THEN
192 CALL XERBLA( 'ZLA_GERCOND_C', -INFO )
196 * Compute norm of op(A)*op2(C).
204 TMP = TMP + CABS1( A( I, J ) ) / C( J )
208 TMP = TMP + CABS1( A( I, J ) )
212 ANORM = MAX( ANORM, TMP )
219 TMP = TMP + CABS1( A( J, I ) ) / C( J )
223 TMP = TMP + CABS1( A( J, I ) )
227 ANORM = MAX( ANORM, TMP )
231 * Quick return if possible.
234 ZLA_GERCOND_C = 1.0D+0
236 ELSE IF( ANORM .EQ. 0.0D+0 ) THEN
240 * Estimate the norm of inv(op(A)).
246 CALL ZLACN2( N, WORK( N+1 ), WORK, AINVNM, KASE, ISAVE )
253 WORK( I ) = WORK( I ) * RWORK( I )
257 CALL ZGETRS( 'No transpose', N, 1, AF, LDAF, IPIV,
260 CALL ZGETRS( 'Conjugate transpose', N, 1, AF, LDAF, IPIV,
264 * Multiply by inv(C).
268 WORK( I ) = WORK( I ) * C( I )
273 * Multiply by inv(C**H).
277 WORK( I ) = WORK( I ) * C( I )
282 CALL ZGETRS( 'Conjugate transpose', N, 1, AF, LDAF, IPIV,
285 CALL ZGETRS( 'No transpose', N, 1, AF, LDAF, IPIV,
292 WORK( I ) = WORK( I ) * RWORK( I )
298 * Compute the estimate of the reciprocal condition number.
300 IF( AINVNM .NE. 0.0D+0 )
301 $ ZLA_GERCOND_C = 1.0D+0 / AINVNM