Annotation of rpl/lapack/lapack/zlansp.f, revision 1.13
1.11 bertrand 1: *> \brief \b ZLANSP returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a symmetric matrix supplied in packed form.
1.8 bertrand 2: *
3: * =========== DOCUMENTATION ===========
4: *
5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
7: *
8: *> \htmlonly
9: *> Download ZLANSP + dependencies
10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zlansp.f">
11: *> [TGZ]</a>
12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zlansp.f">
13: *> [ZIP]</a>
14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zlansp.f">
15: *> [TXT]</a>
16: *> \endhtmlonly
17: *
18: * Definition:
19: * ===========
20: *
21: * DOUBLE PRECISION FUNCTION ZLANSP( NORM, UPLO, N, AP, WORK )
22: *
23: * .. Scalar Arguments ..
24: * CHARACTER NORM, UPLO
25: * INTEGER N
26: * ..
27: * .. Array Arguments ..
28: * DOUBLE PRECISION WORK( * )
29: * COMPLEX*16 AP( * )
30: * ..
31: *
32: *
33: *> \par Purpose:
34: * =============
35: *>
36: *> \verbatim
37: *>
38: *> ZLANSP returns the value of the one norm, or the Frobenius norm, or
39: *> the infinity norm, or the element of largest absolute value of a
40: *> complex symmetric matrix A, supplied in packed form.
41: *> \endverbatim
42: *>
43: *> \return ZLANSP
44: *> \verbatim
45: *>
46: *> ZLANSP = ( max(abs(A(i,j))), NORM = 'M' or 'm'
47: *> (
48: *> ( norm1(A), NORM = '1', 'O' or 'o'
49: *> (
50: *> ( normI(A), NORM = 'I' or 'i'
51: *> (
52: *> ( normF(A), NORM = 'F', 'f', 'E' or 'e'
53: *>
54: *> where norm1 denotes the one norm of a matrix (maximum column sum),
55: *> normI denotes the infinity norm of a matrix (maximum row sum) and
56: *> normF denotes the Frobenius norm of a matrix (square root of sum of
57: *> squares). Note that max(abs(A(i,j))) is not a consistent matrix norm.
58: *> \endverbatim
59: *
60: * Arguments:
61: * ==========
62: *
63: *> \param[in] NORM
64: *> \verbatim
65: *> NORM is CHARACTER*1
66: *> Specifies the value to be returned in ZLANSP as described
67: *> above.
68: *> \endverbatim
69: *>
70: *> \param[in] UPLO
71: *> \verbatim
72: *> UPLO is CHARACTER*1
73: *> Specifies whether the upper or lower triangular part of the
74: *> symmetric matrix A is supplied.
75: *> = 'U': Upper triangular part of A is supplied
76: *> = 'L': Lower triangular part of A is supplied
77: *> \endverbatim
78: *>
79: *> \param[in] N
80: *> \verbatim
81: *> N is INTEGER
82: *> The order of the matrix A. N >= 0. When N = 0, ZLANSP is
83: *> set to zero.
84: *> \endverbatim
85: *>
86: *> \param[in] AP
87: *> \verbatim
88: *> AP is COMPLEX*16 array, dimension (N*(N+1)/2)
89: *> The upper or lower triangle of the symmetric matrix A, packed
90: *> columnwise in a linear array. The j-th column of A is stored
91: *> in the array AP as follows:
92: *> if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
93: *> if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.
94: *> \endverbatim
95: *>
96: *> \param[out] WORK
97: *> \verbatim
98: *> WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)),
99: *> where LWORK >= N when NORM = 'I' or '1' or 'O'; otherwise,
100: *> WORK is not referenced.
101: *> \endverbatim
102: *
103: * Authors:
104: * ========
105: *
106: *> \author Univ. of Tennessee
107: *> \author Univ. of California Berkeley
108: *> \author Univ. of Colorado Denver
109: *> \author NAG Ltd.
110: *
1.11 bertrand 111: *> \date September 2012
1.8 bertrand 112: *
113: *> \ingroup complex16OTHERauxiliary
114: *
115: * =====================================================================
1.1 bertrand 116: DOUBLE PRECISION FUNCTION ZLANSP( NORM, UPLO, N, AP, WORK )
117: *
1.11 bertrand 118: * -- LAPACK auxiliary routine (version 3.4.2) --
1.1 bertrand 119: * -- LAPACK is a software package provided by Univ. of Tennessee, --
120: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.11 bertrand 121: * September 2012
1.1 bertrand 122: *
123: * .. Scalar Arguments ..
124: CHARACTER NORM, UPLO
125: INTEGER N
126: * ..
127: * .. Array Arguments ..
128: DOUBLE PRECISION WORK( * )
129: COMPLEX*16 AP( * )
130: * ..
131: *
132: * =====================================================================
133: *
134: * .. Parameters ..
135: DOUBLE PRECISION ONE, ZERO
136: PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 )
137: * ..
138: * .. Local Scalars ..
139: INTEGER I, J, K
140: DOUBLE PRECISION ABSA, SCALE, SUM, VALUE
141: * ..
142: * .. External Functions ..
1.11 bertrand 143: LOGICAL LSAME, DISNAN
144: EXTERNAL LSAME, DISNAN
1.1 bertrand 145: * ..
146: * .. External Subroutines ..
147: EXTERNAL ZLASSQ
148: * ..
149: * .. Intrinsic Functions ..
1.11 bertrand 150: INTRINSIC ABS, DBLE, DIMAG, SQRT
1.1 bertrand 151: * ..
152: * .. Executable Statements ..
153: *
154: IF( N.EQ.0 ) THEN
155: VALUE = ZERO
156: ELSE IF( LSAME( NORM, 'M' ) ) THEN
157: *
158: * Find max(abs(A(i,j))).
159: *
160: VALUE = ZERO
161: IF( LSAME( UPLO, 'U' ) ) THEN
162: K = 1
163: DO 20 J = 1, N
164: DO 10 I = K, K + J - 1
1.11 bertrand 165: SUM = ABS( AP( I ) )
166: IF( VALUE .LT. SUM .OR. DISNAN( SUM ) ) VALUE = SUM
1.1 bertrand 167: 10 CONTINUE
168: K = K + J
169: 20 CONTINUE
170: ELSE
171: K = 1
172: DO 40 J = 1, N
173: DO 30 I = K, K + N - J
1.11 bertrand 174: SUM = ABS( AP( I ) )
175: IF( VALUE .LT. SUM .OR. DISNAN( SUM ) ) VALUE = SUM
1.1 bertrand 176: 30 CONTINUE
177: K = K + N - J + 1
178: 40 CONTINUE
179: END IF
180: ELSE IF( ( LSAME( NORM, 'I' ) ) .OR. ( LSAME( NORM, 'O' ) ) .OR.
181: $ ( NORM.EQ.'1' ) ) THEN
182: *
183: * Find normI(A) ( = norm1(A), since A is symmetric).
184: *
185: VALUE = ZERO
186: K = 1
187: IF( LSAME( UPLO, 'U' ) ) THEN
188: DO 60 J = 1, N
189: SUM = ZERO
190: DO 50 I = 1, J - 1
191: ABSA = ABS( AP( K ) )
192: SUM = SUM + ABSA
193: WORK( I ) = WORK( I ) + ABSA
194: K = K + 1
195: 50 CONTINUE
196: WORK( J ) = SUM + ABS( AP( K ) )
197: K = K + 1
198: 60 CONTINUE
199: DO 70 I = 1, N
1.11 bertrand 200: SUM = WORK( I )
201: IF( VALUE .LT. SUM .OR. DISNAN( SUM ) ) VALUE = SUM
1.1 bertrand 202: 70 CONTINUE
203: ELSE
204: DO 80 I = 1, N
205: WORK( I ) = ZERO
206: 80 CONTINUE
207: DO 100 J = 1, N
208: SUM = WORK( J ) + ABS( AP( K ) )
209: K = K + 1
210: DO 90 I = J + 1, N
211: ABSA = ABS( AP( K ) )
212: SUM = SUM + ABSA
213: WORK( I ) = WORK( I ) + ABSA
214: K = K + 1
215: 90 CONTINUE
1.11 bertrand 216: IF( VALUE .LT. SUM .OR. DISNAN( SUM ) ) VALUE = SUM
1.1 bertrand 217: 100 CONTINUE
218: END IF
219: ELSE IF( ( LSAME( NORM, 'F' ) ) .OR. ( LSAME( NORM, 'E' ) ) ) THEN
220: *
221: * Find normF(A).
222: *
223: SCALE = ZERO
224: SUM = ONE
225: K = 2
226: IF( LSAME( UPLO, 'U' ) ) THEN
227: DO 110 J = 2, N
228: CALL ZLASSQ( J-1, AP( K ), 1, SCALE, SUM )
229: K = K + J
230: 110 CONTINUE
231: ELSE
232: DO 120 J = 1, N - 1
233: CALL ZLASSQ( N-J, AP( K ), 1, SCALE, SUM )
234: K = K + N - J + 1
235: 120 CONTINUE
236: END IF
237: SUM = 2*SUM
238: K = 1
239: DO 130 I = 1, N
240: IF( DBLE( AP( K ) ).NE.ZERO ) THEN
241: ABSA = ABS( DBLE( AP( K ) ) )
242: IF( SCALE.LT.ABSA ) THEN
243: SUM = ONE + SUM*( SCALE / ABSA )**2
244: SCALE = ABSA
245: ELSE
246: SUM = SUM + ( ABSA / SCALE )**2
247: END IF
248: END IF
249: IF( DIMAG( AP( K ) ).NE.ZERO ) THEN
250: ABSA = ABS( DIMAG( AP( K ) ) )
251: IF( SCALE.LT.ABSA ) THEN
252: SUM = ONE + SUM*( SCALE / ABSA )**2
253: SCALE = ABSA
254: ELSE
255: SUM = SUM + ( ABSA / SCALE )**2
256: END IF
257: END IF
258: IF( LSAME( UPLO, 'U' ) ) THEN
259: K = K + I + 1
260: ELSE
261: K = K + N - I + 1
262: END IF
263: 130 CONTINUE
264: VALUE = SCALE*SQRT( SUM )
265: END IF
266: *
267: ZLANSP = VALUE
268: RETURN
269: *
270: * End of ZLANSP
271: *
272: END
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