1: SUBROUTINE ZTFTTR( TRANSR, UPLO, N, ARF, A, LDA, INFO )
2: *
3: * -- LAPACK routine (version 3.3.0) --
4: *
5: * -- Contributed by Fred Gustavson of the IBM Watson Research Center --
6: * November 2010
7: *
8: * -- LAPACK is a software package provided by Univ. of Tennessee, --
9: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
10: *
11: * .. Scalar Arguments ..
12: CHARACTER TRANSR, UPLO
13: INTEGER INFO, N, LDA
14: * ..
15: * .. Array Arguments ..
16: COMPLEX*16 A( 0: LDA-1, 0: * ), ARF( 0: * )
17: * ..
18: *
19: * Purpose
20: * =======
21: *
22: * ZTFTTR copies a triangular matrix A from rectangular full packed
23: * format (TF) to standard full format (TR).
24: *
25: * Arguments
26: * =========
27: *
28: * TRANSR (input) CHARACTER*1
29: * = 'N': ARF is in Normal format;
30: * = 'C': ARF is in Conjugate-transpose format;
31: *
32: * UPLO (input) CHARACTER*1
33: * = 'U': A is upper triangular;
34: * = 'L': A is lower triangular.
35: *
36: * N (input) INTEGER
37: * The order of the matrix A. N >= 0.
38: *
39: * ARF (input) COMPLEX*16 array, dimension ( N*(N+1)/2 ),
40: * On entry, the upper or lower triangular matrix A stored in
41: * RFP format. For a further discussion see Notes below.
42: *
43: * A (output) COMPLEX*16 array, dimension ( LDA, N )
44: * On exit, the triangular matrix A. If UPLO = 'U', the
45: * leading N-by-N upper triangular part of the array A contains
46: * the upper triangular matrix, and the strictly lower
47: * triangular part of A is not referenced. If UPLO = 'L', the
48: * leading N-by-N lower triangular part of the array A contains
49: * the lower triangular matrix, and the strictly upper
50: * triangular part of A is not referenced.
51: *
52: * LDA (input) INTEGER
53: * The leading dimension of the array A. LDA >= max(1,N).
54: *
55: * INFO (output) INTEGER
56: * = 0: successful exit
57: * < 0: if INFO = -i, the i-th argument had an illegal value
58: *
59: * Further Details
60: * ===============
61: *
62: * We first consider Standard Packed Format when N is even.
63: * We give an example where N = 6.
64: *
65: * AP is Upper AP is Lower
66: *
67: * 00 01 02 03 04 05 00
68: * 11 12 13 14 15 10 11
69: * 22 23 24 25 20 21 22
70: * 33 34 35 30 31 32 33
71: * 44 45 40 41 42 43 44
72: * 55 50 51 52 53 54 55
73: *
74: *
75: * Let TRANSR = 'N'. RFP holds AP as follows:
76: * For UPLO = 'U' the upper trapezoid A(0:5,0:2) consists of the last
77: * three columns of AP upper. The lower triangle A(4:6,0:2) consists of
78: * conjugate-transpose of the first three columns of AP upper.
79: * For UPLO = 'L' the lower trapezoid A(1:6,0:2) consists of the first
80: * three columns of AP lower. The upper triangle A(0:2,0:2) consists of
81: * conjugate-transpose of the last three columns of AP lower.
82: * To denote conjugate we place -- above the element. This covers the
83: * case N even and TRANSR = 'N'.
84: *
85: * RFP A RFP A
86: *
87: * -- -- --
88: * 03 04 05 33 43 53
89: * -- --
90: * 13 14 15 00 44 54
91: * --
92: * 23 24 25 10 11 55
93: *
94: * 33 34 35 20 21 22
95: * --
96: * 00 44 45 30 31 32
97: * -- --
98: * 01 11 55 40 41 42
99: * -- -- --
100: * 02 12 22 50 51 52
101: *
102: * Now let TRANSR = 'C'. RFP A in both UPLO cases is just the conjugate-
103: * transpose of RFP A above. One therefore gets:
104: *
105: *
106: * RFP A RFP A
107: *
108: * -- -- -- -- -- -- -- -- -- --
109: * 03 13 23 33 00 01 02 33 00 10 20 30 40 50
110: * -- -- -- -- -- -- -- -- -- --
111: * 04 14 24 34 44 11 12 43 44 11 21 31 41 51
112: * -- -- -- -- -- -- -- -- -- --
113: * 05 15 25 35 45 55 22 53 54 55 22 32 42 52
114: *
115: *
116: * We next consider Standard Packed Format when N is odd.
117: * We give an example where N = 5.
118: *
119: * AP is Upper AP is Lower
120: *
121: * 00 01 02 03 04 00
122: * 11 12 13 14 10 11
123: * 22 23 24 20 21 22
124: * 33 34 30 31 32 33
125: * 44 40 41 42 43 44
126: *
127: *
128: * Let TRANSR = 'N'. RFP holds AP as follows:
129: * For UPLO = 'U' the upper trapezoid A(0:4,0:2) consists of the last
130: * three columns of AP upper. The lower triangle A(3:4,0:1) consists of
131: * conjugate-transpose of the first two columns of AP upper.
132: * For UPLO = 'L' the lower trapezoid A(0:4,0:2) consists of the first
133: * three columns of AP lower. The upper triangle A(0:1,1:2) consists of
134: * conjugate-transpose of the last two columns of AP lower.
135: * To denote conjugate we place -- above the element. This covers the
136: * case N odd and TRANSR = 'N'.
137: *
138: * RFP A RFP A
139: *
140: * -- --
141: * 02 03 04 00 33 43
142: * --
143: * 12 13 14 10 11 44
144: *
145: * 22 23 24 20 21 22
146: * --
147: * 00 33 34 30 31 32
148: * -- --
149: * 01 11 44 40 41 42
150: *
151: * Now let TRANSR = 'C'. RFP A in both UPLO cases is just the conjugate-
152: * transpose of RFP A above. One therefore gets:
153: *
154: *
155: * RFP A RFP A
156: *
157: * -- -- -- -- -- -- -- -- --
158: * 02 12 22 00 01 00 10 20 30 40 50
159: * -- -- -- -- -- -- -- -- --
160: * 03 13 23 33 11 33 11 21 31 41 51
161: * -- -- -- -- -- -- -- -- --
162: * 04 14 24 34 44 43 44 22 32 42 52
163: *
164: * =====================================================================
165: *
166: * .. Parameters ..
167: * ..
168: * .. Local Scalars ..
169: LOGICAL LOWER, NISODD, NORMALTRANSR
170: INTEGER N1, N2, K, NT, NX2, NP1X2
171: INTEGER I, J, L, IJ
172: * ..
173: * .. External Functions ..
174: LOGICAL LSAME
175: EXTERNAL LSAME
176: * ..
177: * .. External Subroutines ..
178: EXTERNAL XERBLA
179: * ..
180: * .. Intrinsic Functions ..
181: INTRINSIC DCONJG, MAX, MOD
182: * ..
183: * .. Executable Statements ..
184: *
185: * Test the input parameters.
186: *
187: INFO = 0
188: NORMALTRANSR = LSAME( TRANSR, 'N' )
189: LOWER = LSAME( UPLO, 'L' )
190: IF( .NOT.NORMALTRANSR .AND. .NOT.LSAME( TRANSR, 'C' ) ) THEN
191: INFO = -1
192: ELSE IF( .NOT.LOWER .AND. .NOT.LSAME( UPLO, 'U' ) ) THEN
193: INFO = -2
194: ELSE IF( N.LT.0 ) THEN
195: INFO = -3
196: ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
197: INFO = -6
198: END IF
199: IF( INFO.NE.0 ) THEN
200: CALL XERBLA( 'ZTFTTR', -INFO )
201: RETURN
202: END IF
203: *
204: * Quick return if possible
205: *
206: IF( N.LE.1 ) THEN
207: IF( N.EQ.1 ) THEN
208: IF( NORMALTRANSR ) THEN
209: A( 0, 0 ) = ARF( 0 )
210: ELSE
211: A( 0, 0 ) = DCONJG( ARF( 0 ) )
212: END IF
213: END IF
214: RETURN
215: END IF
216: *
217: * Size of array ARF(1:2,0:nt-1)
218: *
219: NT = N*( N+1 ) / 2
220: *
221: * set N1 and N2 depending on LOWER: for N even N1=N2=K
222: *
223: IF( LOWER ) THEN
224: N2 = N / 2
225: N1 = N - N2
226: ELSE
227: N1 = N / 2
228: N2 = N - N1
229: END IF
230: *
231: * If N is odd, set NISODD = .TRUE., LDA=N+1 and A is (N+1)--by--K2.
232: * If N is even, set K = N/2 and NISODD = .FALSE., LDA=N and A is
233: * N--by--(N+1)/2.
234: *
235: IF( MOD( N, 2 ).EQ.0 ) THEN
236: K = N / 2
237: NISODD = .FALSE.
238: IF( .NOT.LOWER )
239: + NP1X2 = N + N + 2
240: ELSE
241: NISODD = .TRUE.
242: IF( .NOT.LOWER )
243: + NX2 = N + N
244: END IF
245: *
246: IF( NISODD ) THEN
247: *
248: * N is odd
249: *
250: IF( NORMALTRANSR ) THEN
251: *
252: * N is odd and TRANSR = 'N'
253: *
254: IF( LOWER ) THEN
255: *
256: * SRPA for LOWER, NORMAL and N is odd ( a(0:n-1,0:n1-1) )
257: * T1 -> a(0,0), T2 -> a(0,1), S -> a(n1,0)
258: * T1 -> a(0), T2 -> a(n), S -> a(n1); lda=n
259: *
260: IJ = 0
261: DO J = 0, N2
262: DO I = N1, N2 + J
263: A( N2+J, I ) = DCONJG( ARF( IJ ) )
264: IJ = IJ + 1
265: END DO
266: DO I = J, N - 1
267: A( I, J ) = ARF( IJ )
268: IJ = IJ + 1
269: END DO
270: END DO
271: *
272: ELSE
273: *
274: * SRPA for UPPER, NORMAL and N is odd ( a(0:n-1,0:n2-1)
275: * T1 -> a(n1+1,0), T2 -> a(n1,0), S -> a(0,0)
276: * T1 -> a(n2), T2 -> a(n1), S -> a(0); lda=n
277: *
278: IJ = NT - N
279: DO J = N - 1, N1, -1
280: DO I = 0, J
281: A( I, J ) = ARF( IJ )
282: IJ = IJ + 1
283: END DO
284: DO L = J - N1, N1 - 1
285: A( J-N1, L ) = DCONJG( ARF( IJ ) )
286: IJ = IJ + 1
287: END DO
288: IJ = IJ - NX2
289: END DO
290: *
291: END IF
292: *
293: ELSE
294: *
295: * N is odd and TRANSR = 'C'
296: *
297: IF( LOWER ) THEN
298: *
299: * SRPA for LOWER, TRANSPOSE and N is odd
300: * T1 -> A(0,0) , T2 -> A(1,0) , S -> A(0,n1)
301: * T1 -> A(0+0) , T2 -> A(1+0) , S -> A(0+n1*n1); lda=n1
302: *
303: IJ = 0
304: DO J = 0, N2 - 1
305: DO I = 0, J
306: A( J, I ) = DCONJG( ARF( IJ ) )
307: IJ = IJ + 1
308: END DO
309: DO I = N1 + J, N - 1
310: A( I, N1+J ) = ARF( IJ )
311: IJ = IJ + 1
312: END DO
313: END DO
314: DO J = N2, N - 1
315: DO I = 0, N1 - 1
316: A( J, I ) = DCONJG( ARF( IJ ) )
317: IJ = IJ + 1
318: END DO
319: END DO
320: *
321: ELSE
322: *
323: * SRPA for UPPER, TRANSPOSE and N is odd
324: * T1 -> A(0,n1+1), T2 -> A(0,n1), S -> A(0,0)
325: * T1 -> A(n2*n2), T2 -> A(n1*n2), S -> A(0); lda = n2
326: *
327: IJ = 0
328: DO J = 0, N1
329: DO I = N1, N - 1
330: A( J, I ) = DCONJG( ARF( IJ ) )
331: IJ = IJ + 1
332: END DO
333: END DO
334: DO J = 0, N1 - 1
335: DO I = 0, J
336: A( I, J ) = ARF( IJ )
337: IJ = IJ + 1
338: END DO
339: DO L = N2 + J, N - 1
340: A( N2+J, L ) = DCONJG( ARF( IJ ) )
341: IJ = IJ + 1
342: END DO
343: END DO
344: *
345: END IF
346: *
347: END IF
348: *
349: ELSE
350: *
351: * N is even
352: *
353: IF( NORMALTRANSR ) THEN
354: *
355: * N is even and TRANSR = 'N'
356: *
357: IF( LOWER ) THEN
358: *
359: * SRPA for LOWER, NORMAL, and N is even ( a(0:n,0:k-1) )
360: * T1 -> a(1,0), T2 -> a(0,0), S -> a(k+1,0)
361: * T1 -> a(1), T2 -> a(0), S -> a(k+1); lda=n+1
362: *
363: IJ = 0
364: DO J = 0, K - 1
365: DO I = K, K + J
366: A( K+J, I ) = DCONJG( ARF( IJ ) )
367: IJ = IJ + 1
368: END DO
369: DO I = J, N - 1
370: A( I, J ) = ARF( IJ )
371: IJ = IJ + 1
372: END DO
373: END DO
374: *
375: ELSE
376: *
377: * SRPA for UPPER, NORMAL, and N is even ( a(0:n,0:k-1) )
378: * T1 -> a(k+1,0) , T2 -> a(k,0), S -> a(0,0)
379: * T1 -> a(k+1), T2 -> a(k), S -> a(0); lda=n+1
380: *
381: IJ = NT - N - 1
382: DO J = N - 1, K, -1
383: DO I = 0, J
384: A( I, J ) = ARF( IJ )
385: IJ = IJ + 1
386: END DO
387: DO L = J - K, K - 1
388: A( J-K, L ) = DCONJG( ARF( IJ ) )
389: IJ = IJ + 1
390: END DO
391: IJ = IJ - NP1X2
392: END DO
393: *
394: END IF
395: *
396: ELSE
397: *
398: * N is even and TRANSR = 'C'
399: *
400: IF( LOWER ) THEN
401: *
402: * SRPA for LOWER, TRANSPOSE and N is even (see paper, A=B)
403: * T1 -> A(0,1) , T2 -> A(0,0) , S -> A(0,k+1) :
404: * T1 -> A(0+k) , T2 -> A(0+0) , S -> A(0+k*(k+1)); lda=k
405: *
406: IJ = 0
407: J = K
408: DO I = K, N - 1
409: A( I, J ) = ARF( IJ )
410: IJ = IJ + 1
411: END DO
412: DO J = 0, K - 2
413: DO I = 0, J
414: A( J, I ) = DCONJG( ARF( IJ ) )
415: IJ = IJ + 1
416: END DO
417: DO I = K + 1 + J, N - 1
418: A( I, K+1+J ) = ARF( IJ )
419: IJ = IJ + 1
420: END DO
421: END DO
422: DO J = K - 1, N - 1
423: DO I = 0, K - 1
424: A( J, I ) = DCONJG( ARF( IJ ) )
425: IJ = IJ + 1
426: END DO
427: END DO
428: *
429: ELSE
430: *
431: * SRPA for UPPER, TRANSPOSE and N is even (see paper, A=B)
432: * T1 -> A(0,k+1) , T2 -> A(0,k) , S -> A(0,0)
433: * T1 -> A(0+k*(k+1)) , T2 -> A(0+k*k) , S -> A(0+0)); lda=k
434: *
435: IJ = 0
436: DO J = 0, K
437: DO I = K, N - 1
438: A( J, I ) = DCONJG( ARF( IJ ) )
439: IJ = IJ + 1
440: END DO
441: END DO
442: DO J = 0, K - 2
443: DO I = 0, J
444: A( I, J ) = ARF( IJ )
445: IJ = IJ + 1
446: END DO
447: DO L = K + 1 + J, N - 1
448: A( K+1+J, L ) = DCONJG( ARF( IJ ) )
449: IJ = IJ + 1
450: END DO
451: END DO
452: *
453: * Note that here J = K-1
454: *
455: DO I = 0, J
456: A( I, J ) = ARF( IJ )
457: IJ = IJ + 1
458: END DO
459: *
460: END IF
461: *
462: END IF
463: *
464: END IF
465: *
466: RETURN
467: *
468: * End of ZTFTTR
469: *
470: END
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