LAPACK 3.12.0 LAPACK: Linear Algebra PACKage
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zlat2c.f
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1*> \brief \b ZLAT2C converts a double complex triangular matrix to a complex triangular matrix.
2*
3* =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6* http://www.netlib.org/lapack/explore-html/
7*
8*> \htmlonly
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15*> [TXT]</a>
16*> \endhtmlonly
17*
18* Definition:
19* ===========
20*
21* SUBROUTINE ZLAT2C( UPLO, N, A, LDA, SA, LDSA, INFO )
22*
23* .. Scalar Arguments ..
24* CHARACTER UPLO
25* INTEGER INFO, LDA, LDSA, N
26* ..
27* .. Array Arguments ..
28* COMPLEX SA( LDSA, * )
29* COMPLEX*16 A( LDA, * )
30* ..
31*
32*
33*> \par Purpose:
34* =============
35*>
36*> \verbatim
37*>
38*> ZLAT2C converts a COMPLEX*16 triangular matrix, SA, to a COMPLEX
39*> triangular matrix, A.
40*>
41*> RMAX is the overflow for the SINGLE PRECISION arithmetic
42*> ZLAT2C checks that all the entries of A are between -RMAX and
43*> RMAX. If not the conversion is aborted and a flag is raised.
44*>
45*> This is an auxiliary routine so there is no argument checking.
46*> \endverbatim
47*
48* Arguments:
49* ==========
50*
51*> \param[in] UPLO
52*> \verbatim
53*> UPLO is CHARACTER*1
54*> = 'U': A is upper triangular;
55*> = 'L': A is lower triangular.
56*> \endverbatim
57*>
58*> \param[in] N
59*> \verbatim
60*> N is INTEGER
61*> The number of rows and columns of the matrix A. N >= 0.
62*> \endverbatim
63*>
64*> \param[in] A
65*> \verbatim
66*> A is COMPLEX*16 array, dimension (LDA,N)
67*> On entry, the N-by-N triangular coefficient matrix A.
68*> \endverbatim
69*>
70*> \param[in] LDA
71*> \verbatim
72*> LDA is INTEGER
73*> The leading dimension of the array A. LDA >= max(1,N).
74*> \endverbatim
75*>
76*> \param[out] SA
77*> \verbatim
78*> SA is COMPLEX array, dimension (LDSA,N)
79*> Only the UPLO part of SA is referenced. On exit, if INFO=0,
80*> the N-by-N coefficient matrix SA; if INFO>0, the content of
81*> the UPLO part of SA is unspecified.
82*> \endverbatim
83*>
84*> \param[in] LDSA
85*> \verbatim
86*> LDSA is INTEGER
87*> The leading dimension of the array SA. LDSA >= max(1,M).
88*> \endverbatim
89*>
90*> \param[out] INFO
91*> \verbatim
92*> INFO is INTEGER
93*> = 0: successful exit.
94*> = 1: an entry of the matrix A is greater than the SINGLE
95*> PRECISION overflow threshold, in this case, the content
96*> of the UPLO part of SA in exit is unspecified.
97*> \endverbatim
98*
99* Authors:
100* ========
101*
102*> \author Univ. of Tennessee
103*> \author Univ. of California Berkeley
104*> \author Univ. of Colorado Denver
105*> \author NAG Ltd.
106*
107*> \ingroup _lat2_
108*
109* =====================================================================
110 SUBROUTINE zlat2c( UPLO, N, A, LDA, SA, LDSA, INFO )
111*
112* -- LAPACK auxiliary routine --
113* -- LAPACK is a software package provided by Univ. of Tennessee, --
114* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
115*
116* .. Scalar Arguments ..
117 CHARACTER UPLO
118 INTEGER INFO, LDA, LDSA, N
119* ..
120* .. Array Arguments ..
121 COMPLEX SA( LDSA, * )
122 COMPLEX*16 A( LDA, * )
123* ..
124*
125* =====================================================================
126*
127* .. Local Scalars ..
128 INTEGER I, J
129 DOUBLE PRECISION RMAX
130 LOGICAL UPPER
131* ..
132* .. Intrinsic Functions ..
133 INTRINSIC dble, dimag, cmplx
134* ..
135* .. External Functions ..
136 REAL SLAMCH
137 LOGICAL LSAME
138 EXTERNAL slamch, lsame
139* ..
140* .. Executable Statements ..
141*
142 rmax = slamch( 'O' )
143 upper = lsame( uplo, 'U' )
144 IF( upper ) THEN
145 DO 20 j = 1, n
146 DO 10 i = 1, j
147 IF( ( dble( a( i, j ) ).LT.-rmax ) .OR.
148 \$ ( dble( a( i, j ) ).GT.rmax ) .OR.
149 \$ ( dimag( a( i, j ) ).LT.-rmax ) .OR.
150 \$ ( dimag( a( i, j ) ).GT.rmax ) ) THEN
151 info = 1
152 GO TO 50
153 END IF
154 sa( i, j ) = cmplx( a( i, j ) )
155 10 CONTINUE
156 20 CONTINUE
157 ELSE
158 DO 40 j = 1, n
159 DO 30 i = j, n
160 IF( ( dble( a( i, j ) ).LT.-rmax ) .OR.
161 \$ ( dble( a( i, j ) ).GT.rmax ) .OR.
162 \$ ( dimag( a( i, j ) ).LT.-rmax ) .OR.
163 \$ ( dimag( a( i, j ) ).GT.rmax ) ) THEN
164 info = 1
165 GO TO 50
166 END IF
167 sa( i, j ) = cmplx( a( i, j ) )
168 30 CONTINUE
169 40 CONTINUE
170 END IF
171 50 CONTINUE
172*
173 RETURN
174*
175* End of ZLAT2C
176*
177 END
subroutine zlat2c(uplo, n, a, lda, sa, ldsa, info)
ZLAT2C converts a double complex triangular matrix to a complex triangular matrix.
Definition zlat2c.f:111