1*> \brief \b SLARFB 2* 3* =========== DOCUMENTATION =========== 4* 5* Online html documentation available at 6* http://www.netlib.org/lapack/explore-html/ 7* 8*> \htmlonly 9*> Download SLARFB + dependencies 10*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/slarfb.f"> 11*> [TGZ]</a> 12*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/slarfb.f"> 13*> [ZIP]</a> 14*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/slarfb.f"> 15*> [TXT]</a> 16*> \endhtmlonly 17* 18* Definition: 19* =========== 20* 21* SUBROUTINE SLARFB( SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV, 22* T, LDT, C, LDC, WORK, LDWORK ) 23* 24* .. Scalar Arguments .. 25* CHARACTER DIRECT, SIDE, STOREV, TRANS 26* INTEGER K, LDC, LDT, LDV, LDWORK, M, N 27* .. 28* .. Array Arguments .. 29* REAL C( LDC, * ), T( LDT, * ), V( LDV, * ), 30* $ WORK( LDWORK, * ) 31* .. 32* 33* 34*> \par Purpose: 35* ============= 36*> 37*> \verbatim 38*> 39*> SLARFB applies a real block reflector H or its transpose H**T to a 40*> real m by n matrix C, from either the left or the right. 41*> \endverbatim 42* 43* Arguments: 44* ========== 45* 46*> \param[in] SIDE 47*> \verbatim 48*> SIDE is CHARACTER*1 49*> = 'L': apply H or H**T from the Left 50*> = 'R': apply H or H**T from the Right 51*> \endverbatim 52*> 53*> \param[in] TRANS 54*> \verbatim 55*> TRANS is CHARACTER*1 56*> = 'N': apply H (No transpose) 57*> = 'T': apply H**T (Transpose) 58*> \endverbatim 59*> 60*> \param[in] DIRECT 61*> \verbatim 62*> DIRECT is CHARACTER*1 63*> Indicates how H is formed from a product of elementary 64*> reflectors 65*> = 'F': H = H(1) H(2) . . . H(k) (Forward) 66*> = 'B': H = H(k) . . . H(2) H(1) (Backward) 67*> \endverbatim 68*> 69*> \param[in] STOREV 70*> \verbatim 71*> STOREV is CHARACTER*1 72*> Indicates how the vectors which define the elementary 73*> reflectors are stored: 74*> = 'C': Columnwise 75*> = 'R': Rowwise 76*> \endverbatim 77*> 78*> \param[in] M 79*> \verbatim 80*> M is INTEGER 81*> The number of rows of the matrix C. 82*> \endverbatim 83*> 84*> \param[in] N 85*> \verbatim 86*> N is INTEGER 87*> The number of columns of the matrix C. 88*> \endverbatim 89*> 90*> \param[in] K 91*> \verbatim 92*> K is INTEGER 93*> The order of the matrix T (= the number of elementary 94*> reflectors whose product defines the block reflector). 95*> \endverbatim 96*> 97*> \param[in] V 98*> \verbatim 99*> V is REAL array, dimension 100*> (LDV,K) if STOREV = 'C' 101*> (LDV,M) if STOREV = 'R' and SIDE = 'L' 102*> (LDV,N) if STOREV = 'R' and SIDE = 'R' 103*> The matrix V. See Further Details. 104*> \endverbatim 105*> 106*> \param[in] LDV 107*> \verbatim 108*> LDV is INTEGER 109*> The leading dimension of the array V. 110*> If STOREV = 'C' and SIDE = 'L', LDV >= max(1,M); 111*> if STOREV = 'C' and SIDE = 'R', LDV >= max(1,N); 112*> if STOREV = 'R', LDV >= K. 113*> \endverbatim 114*> 115*> \param[in] T 116*> \verbatim 117*> T is REAL array, dimension (LDT,K) 118*> The triangular k by k matrix T in the representation of the 119*> block reflector. 120*> \endverbatim 121*> 122*> \param[in] LDT 123*> \verbatim 124*> LDT is INTEGER 125*> The leading dimension of the array T. LDT >= K. 126*> \endverbatim 127*> 128*> \param[in,out] C 129*> \verbatim 130*> C is REAL array, dimension (LDC,N) 131*> On entry, the m by n matrix C. 132*> On exit, C is overwritten by H*C or H**T*C or C*H or C*H**T. 133*> \endverbatim 134*> 135*> \param[in] LDC 136*> \verbatim 137*> LDC is INTEGER 138*> The leading dimension of the array C. LDC >= max(1,M). 139*> \endverbatim 140*> 141*> \param[out] WORK 142*> \verbatim 143*> WORK is REAL array, dimension (LDWORK,K) 144*> \endverbatim 145*> 146*> \param[in] LDWORK 147*> \verbatim 148*> LDWORK is INTEGER 149*> The leading dimension of the array WORK. 150*> If SIDE = 'L', LDWORK >= max(1,N); 151*> if SIDE = 'R', LDWORK >= max(1,M). 152*> \endverbatim 153* 154* Authors: 155* ======== 156* 157*> \author Univ. of Tennessee 158*> \author Univ. of California Berkeley 159*> \author Univ. of Colorado Denver 160*> \author NAG Ltd. 161* 162*> \date November 2011 163* 164*> \ingroup realOTHERauxiliary 165* 166*> \par Further Details: 167* ===================== 168*> 169*> \verbatim 170*> 171*> The shape of the matrix V and the storage of the vectors which define 172*> the H(i) is best illustrated by the following example with n = 5 and 173*> k = 3. The elements equal to 1 are not stored; the corresponding 174*> array elements are modified but restored on exit. The rest of the 175*> array is not used. 176*> 177*> DIRECT = 'F' and STOREV = 'C': DIRECT = 'F' and STOREV = 'R': 178*> 179*> V = ( 1 ) V = ( 1 v1 v1 v1 v1 ) 180*> ( v1 1 ) ( 1 v2 v2 v2 ) 181*> ( v1 v2 1 ) ( 1 v3 v3 ) 182*> ( v1 v2 v3 ) 183*> ( v1 v2 v3 ) 184*> 185*> DIRECT = 'B' and STOREV = 'C': DIRECT = 'B' and STOREV = 'R': 186*> 187*> V = ( v1 v2 v3 ) V = ( v1 v1 1 ) 188*> ( v1 v2 v3 ) ( v2 v2 v2 1 ) 189*> ( 1 v2 v3 ) ( v3 v3 v3 v3 1 ) 190*> ( 1 v3 ) 191*> ( 1 ) 192*> \endverbatim 193*> 194* ===================================================================== 195 SUBROUTINE SLARFB( SIDE, TRANS, DIRECT, STOREV, M, N, K, V, LDV, 196 $ T, LDT, C, LDC, WORK, LDWORK ) 197* 198* -- LAPACK auxiliary routine (version 3.4.0) -- 199* -- LAPACK is a software package provided by Univ. of Tennessee, -- 200* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- 201* November 2011 202* 203* .. Scalar Arguments .. 204 CHARACTER DIRECT, SIDE, STOREV, TRANS 205 INTEGER K, LDC, LDT, LDV, LDWORK, M, N 206* .. 207* .. Array Arguments .. 208 REAL C( LDC, * ), T( LDT, * ), V( LDV, * ), 209 $ WORK( LDWORK, * ) 210* .. 211* 212* ===================================================================== 213* 214* .. Parameters .. 215 REAL ONE 216 PARAMETER ( ONE = 1.0E+0 ) 217* .. 218* .. Local Scalars .. 219 CHARACTER TRANST 220 INTEGER I, J, LASTV, LASTC 221* .. 222* .. External Functions .. 223 LOGICAL LSAME 224 INTEGER ILASLR, ILASLC 225 EXTERNAL LSAME, ILASLR, ILASLC 226* .. 227* .. External Subroutines .. 228 EXTERNAL SCOPY, SGEMM, STRMM 229* .. 230* .. Executable Statements .. 231* 232* Quick return if possible 233* 234 IF( M.LE.0 .OR. N.LE.0 ) 235 $ RETURN 236* 237 IF( LSAME( TRANS, 'N' ) ) THEN 238 TRANST = 'T' 239 ELSE 240 TRANST = 'N' 241 END IF 242* 243 IF( LSAME( STOREV, 'C' ) ) THEN 244* 245 IF( LSAME( DIRECT, 'F' ) ) THEN 246* 247* Let V = ( V1 ) (first K rows) 248* ( V2 ) 249* where V1 is unit lower triangular. 250* 251 IF( LSAME( SIDE, 'L' ) ) THEN 252* 253* Form H * C or H**T * C where C = ( C1 ) 254* ( C2 ) 255* 256 LASTV = MAX( K, ILASLR( M, K, V, LDV ) ) 257 LASTC = ILASLC( LASTV, N, C, LDC ) 258* 259* W := C**T * V = (C1**T * V1 + C2**T * V2) (stored in WORK) 260* 261* W := C1**T 262* 263 DO 10 J = 1, K 264 CALL SCOPY( LASTC, C( J, 1 ), LDC, WORK( 1, J ), 1 ) 265 10 CONTINUE 266* 267* W := W * V1 268* 269 CALL STRMM( 'Right', 'Lower', 'No transpose', 'Unit', 270 $ LASTC, K, ONE, V, LDV, WORK, LDWORK ) 271 IF( LASTV.GT.K ) THEN 272* 273* W := W + C2**T *V2 274* 275 CALL SGEMM( 'Transpose', 'No transpose', 276 $ LASTC, K, LASTV-K, 277 $ ONE, C( K+1, 1 ), LDC, V( K+1, 1 ), LDV, 278 $ ONE, WORK, LDWORK ) 279 END IF 280* 281* W := W * T**T or W * T 282* 283 CALL STRMM( 'Right', 'Upper', TRANST, 'Non-unit', 284 $ LASTC, K, ONE, T, LDT, WORK, LDWORK ) 285* 286* C := C - V * W**T 287* 288 IF( LASTV.GT.K ) THEN 289* 290* C2 := C2 - V2 * W**T 291* 292 CALL SGEMM( 'No transpose', 'Transpose', 293 $ LASTV-K, LASTC, K, 294 $ -ONE, V( K+1, 1 ), LDV, WORK, LDWORK, ONE, 295 $ C( K+1, 1 ), LDC ) 296 END IF 297* 298* W := W * V1**T 299* 300 CALL STRMM( 'Right', 'Lower', 'Transpose', 'Unit', 301 $ LASTC, K, ONE, V, LDV, WORK, LDWORK ) 302* 303* C1 := C1 - W**T 304* 305 DO 30 J = 1, K 306 DO 20 I = 1, LASTC 307 C( J, I ) = C( J, I ) - WORK( I, J ) 308 20 CONTINUE 309 30 CONTINUE 310* 311 ELSE IF( LSAME( SIDE, 'R' ) ) THEN 312* 313* Form C * H or C * H**T where C = ( C1 C2 ) 314* 315 LASTV = MAX( K, ILASLR( N, K, V, LDV ) ) 316 LASTC = ILASLR( M, LASTV, C, LDC ) 317* 318* W := C * V = (C1*V1 + C2*V2) (stored in WORK) 319* 320* W := C1 321* 322 DO 40 J = 1, K 323 CALL SCOPY( LASTC, C( 1, J ), 1, WORK( 1, J ), 1 ) 324 40 CONTINUE 325* 326* W := W * V1 327* 328 CALL STRMM( 'Right', 'Lower', 'No transpose', 'Unit', 329 $ LASTC, K, ONE, V, LDV, WORK, LDWORK ) 330 IF( LASTV.GT.K ) THEN 331* 332* W := W + C2 * V2 333* 334 CALL SGEMM( 'No transpose', 'No transpose', 335 $ LASTC, K, LASTV-K, 336 $ ONE, C( 1, K+1 ), LDC, V( K+1, 1 ), LDV, 337 $ ONE, WORK, LDWORK ) 338 END IF 339* 340* W := W * T or W * T**T 341* 342 CALL STRMM( 'Right', 'Upper', TRANS, 'Non-unit', 343 $ LASTC, K, ONE, T, LDT, WORK, LDWORK ) 344* 345* C := C - W * V**T 346* 347 IF( LASTV.GT.K ) THEN 348* 349* C2 := C2 - W * V2**T 350* 351 CALL SGEMM( 'No transpose', 'Transpose', 352 $ LASTC, LASTV-K, K, 353 $ -ONE, WORK, LDWORK, V( K+1, 1 ), LDV, ONE, 354 $ C( 1, K+1 ), LDC ) 355 END IF 356* 357* W := W * V1**T 358* 359 CALL STRMM( 'Right', 'Lower', 'Transpose', 'Unit', 360 $ LASTC, K, ONE, V, LDV, WORK, LDWORK ) 361* 362* C1 := C1 - W 363* 364 DO 60 J = 1, K 365 DO 50 I = 1, LASTC 366 C( I, J ) = C( I, J ) - WORK( I, J ) 367 50 CONTINUE 368 60 CONTINUE 369 END IF 370* 371 ELSE 372* 373* Let V = ( V1 ) 374* ( V2 ) (last K rows) 375* where V2 is unit upper triangular. 376* 377 IF( LSAME( SIDE, 'L' ) ) THEN 378* 379* Form H * C or H**T * C where C = ( C1 ) 380* ( C2 ) 381* 382 LASTV = MAX( K, ILASLR( M, K, V, LDV ) ) 383 LASTC = ILASLC( LASTV, N, C, LDC ) 384* 385* W := C**T * V = (C1**T * V1 + C2**T * V2) (stored in WORK) 386* 387* W := C2**T 388* 389 DO 70 J = 1, K 390 CALL SCOPY( LASTC, C( LASTV-K+J, 1 ), LDC, 391 $ WORK( 1, J ), 1 ) 392 70 CONTINUE 393* 394* W := W * V2 395* 396 CALL STRMM( 'Right', 'Upper', 'No transpose', 'Unit', 397 $ LASTC, K, ONE, V( LASTV-K+1, 1 ), LDV, 398 $ WORK, LDWORK ) 399 IF( LASTV.GT.K ) THEN 400* 401* W := W + C1**T*V1 402* 403 CALL SGEMM( 'Transpose', 'No transpose', 404 $ LASTC, K, LASTV-K, ONE, C, LDC, V, LDV, 405 $ ONE, WORK, LDWORK ) 406 END IF 407* 408* W := W * T**T or W * T 409* 410 CALL STRMM( 'Right', 'Lower', TRANST, 'Non-unit', 411 $ LASTC, K, ONE, T, LDT, WORK, LDWORK ) 412* 413* C := C - V * W**T 414* 415 IF( LASTV.GT.K ) THEN 416* 417* C1 := C1 - V1 * W**T 418* 419 CALL SGEMM( 'No transpose', 'Transpose', 420 $ LASTV-K, LASTC, K, -ONE, V, LDV, WORK, LDWORK, 421 $ ONE, C, LDC ) 422 END IF 423* 424* W := W * V2**T 425* 426 CALL STRMM( 'Right', 'Upper', 'Transpose', 'Unit', 427 $ LASTC, K, ONE, V( LASTV-K+1, 1 ), LDV, 428 $ WORK, LDWORK ) 429* 430* C2 := C2 - W**T 431* 432 DO 90 J = 1, K 433 DO 80 I = 1, LASTC 434 C( LASTV-K+J, I ) = C( LASTV-K+J, I ) - WORK(I, J) 435 80 CONTINUE 436 90 CONTINUE 437* 438 ELSE IF( LSAME( SIDE, 'R' ) ) THEN 439* 440* Form C * H or C * H**T where C = ( C1 C2 ) 441* 442 LASTV = MAX( K, ILASLR( N, K, V, LDV ) ) 443 LASTC = ILASLR( M, LASTV, C, LDC ) 444* 445* W := C * V = (C1*V1 + C2*V2) (stored in WORK) 446* 447* W := C2 448* 449 DO 100 J = 1, K 450 CALL SCOPY( LASTC, C( 1, N-K+J ), 1, WORK( 1, J ), 1 ) 451 100 CONTINUE 452* 453* W := W * V2 454* 455 CALL STRMM( 'Right', 'Upper', 'No transpose', 'Unit', 456 $ LASTC, K, ONE, V( LASTV-K+1, 1 ), LDV, 457 $ WORK, LDWORK ) 458 IF( LASTV.GT.K ) THEN 459* 460* W := W + C1 * V1 461* 462 CALL SGEMM( 'No transpose', 'No transpose', 463 $ LASTC, K, LASTV-K, ONE, C, LDC, V, LDV, 464 $ ONE, WORK, LDWORK ) 465 END IF 466* 467* W := W * T or W * T**T 468* 469 CALL STRMM( 'Right', 'Lower', TRANS, 'Non-unit', 470 $ LASTC, K, ONE, T, LDT, WORK, LDWORK ) 471* 472* C := C - W * V**T 473* 474 IF( LASTV.GT.K ) THEN 475* 476* C1 := C1 - W * V1**T 477* 478 CALL SGEMM( 'No transpose', 'Transpose', 479 $ LASTC, LASTV-K, K, -ONE, WORK, LDWORK, V, LDV, 480 $ ONE, C, LDC ) 481 END IF 482* 483* W := W * V2**T 484* 485 CALL STRMM( 'Right', 'Upper', 'Transpose', 'Unit', 486 $ LASTC, K, ONE, V( LASTV-K+1, 1 ), LDV, 487 $ WORK, LDWORK ) 488* 489* C2 := C2 - W 490* 491 DO 120 J = 1, K 492 DO 110 I = 1, LASTC 493 C( I, LASTV-K+J ) = C( I, LASTV-K+J ) - WORK(I, J) 494 110 CONTINUE 495 120 CONTINUE 496 END IF 497 END IF 498* 499 ELSE IF( LSAME( STOREV, 'R' ) ) THEN 500* 501 IF( LSAME( DIRECT, 'F' ) ) THEN 502* 503* Let V = ( V1 V2 ) (V1: first K columns) 504* where V1 is unit upper triangular. 505* 506 IF( LSAME( SIDE, 'L' ) ) THEN 507* 508* Form H * C or H**T * C where C = ( C1 ) 509* ( C2 ) 510* 511 LASTV = MAX( K, ILASLC( K, M, V, LDV ) ) 512 LASTC = ILASLC( LASTV, N, C, LDC ) 513* 514* W := C**T * V**T = (C1**T * V1**T + C2**T * V2**T) (stored in WORK) 515* 516* W := C1**T 517* 518 DO 130 J = 1, K 519 CALL SCOPY( LASTC, C( J, 1 ), LDC, WORK( 1, J ), 1 ) 520 130 CONTINUE 521* 522* W := W * V1**T 523* 524 CALL STRMM( 'Right', 'Upper', 'Transpose', 'Unit', 525 $ LASTC, K, ONE, V, LDV, WORK, LDWORK ) 526 IF( LASTV.GT.K ) THEN 527* 528* W := W + C2**T*V2**T 529* 530 CALL SGEMM( 'Transpose', 'Transpose', 531 $ LASTC, K, LASTV-K, 532 $ ONE, C( K+1, 1 ), LDC, V( 1, K+1 ), LDV, 533 $ ONE, WORK, LDWORK ) 534 END IF 535* 536* W := W * T**T or W * T 537* 538 CALL STRMM( 'Right', 'Upper', TRANST, 'Non-unit', 539 $ LASTC, K, ONE, T, LDT, WORK, LDWORK ) 540* 541* C := C - V**T * W**T 542* 543 IF( LASTV.GT.K ) THEN 544* 545* C2 := C2 - V2**T * W**T 546* 547 CALL SGEMM( 'Transpose', 'Transpose', 548 $ LASTV-K, LASTC, K, 549 $ -ONE, V( 1, K+1 ), LDV, WORK, LDWORK, 550 $ ONE, C( K+1, 1 ), LDC ) 551 END IF 552* 553* W := W * V1 554* 555 CALL STRMM( 'Right', 'Upper', 'No transpose', 'Unit', 556 $ LASTC, K, ONE, V, LDV, WORK, LDWORK ) 557* 558* C1 := C1 - W**T 559* 560 DO 150 J = 1, K 561 DO 140 I = 1, LASTC 562 C( J, I ) = C( J, I ) - WORK( I, J ) 563 140 CONTINUE 564 150 CONTINUE 565* 566 ELSE IF( LSAME( SIDE, 'R' ) ) THEN 567* 568* Form C * H or C * H**T where C = ( C1 C2 ) 569* 570 LASTV = MAX( K, ILASLC( K, N, V, LDV ) ) 571 LASTC = ILASLR( M, LASTV, C, LDC ) 572* 573* W := C * V**T = (C1*V1**T + C2*V2**T) (stored in WORK) 574* 575* W := C1 576* 577 DO 160 J = 1, K 578 CALL SCOPY( LASTC, C( 1, J ), 1, WORK( 1, J ), 1 ) 579 160 CONTINUE 580* 581* W := W * V1**T 582* 583 CALL STRMM( 'Right', 'Upper', 'Transpose', 'Unit', 584 $ LASTC, K, ONE, V, LDV, WORK, LDWORK ) 585 IF( LASTV.GT.K ) THEN 586* 587* W := W + C2 * V2**T 588* 589 CALL SGEMM( 'No transpose', 'Transpose', 590 $ LASTC, K, LASTV-K, 591 $ ONE, C( 1, K+1 ), LDC, V( 1, K+1 ), LDV, 592 $ ONE, WORK, LDWORK ) 593 END IF 594* 595* W := W * T or W * T**T 596* 597 CALL STRMM( 'Right', 'Upper', TRANS, 'Non-unit', 598 $ LASTC, K, ONE, T, LDT, WORK, LDWORK ) 599* 600* C := C - W * V 601* 602 IF( LASTV.GT.K ) THEN 603* 604* C2 := C2 - W * V2 605* 606 CALL SGEMM( 'No transpose', 'No transpose', 607 $ LASTC, LASTV-K, K, 608 $ -ONE, WORK, LDWORK, V( 1, K+1 ), LDV, 609 $ ONE, C( 1, K+1 ), LDC ) 610 END IF 611* 612* W := W * V1 613* 614 CALL STRMM( 'Right', 'Upper', 'No transpose', 'Unit', 615 $ LASTC, K, ONE, V, LDV, WORK, LDWORK ) 616* 617* C1 := C1 - W 618* 619 DO 180 J = 1, K 620 DO 170 I = 1, LASTC 621 C( I, J ) = C( I, J ) - WORK( I, J ) 622 170 CONTINUE 623 180 CONTINUE 624* 625 END IF 626* 627 ELSE 628* 629* Let V = ( V1 V2 ) (V2: last K columns) 630* where V2 is unit lower triangular. 631* 632 IF( LSAME( SIDE, 'L' ) ) THEN 633* 634* Form H * C or H**T * C where C = ( C1 ) 635* ( C2 ) 636* 637 LASTV = MAX( K, ILASLC( K, M, V, LDV ) ) 638 LASTC = ILASLC( LASTV, N, C, LDC ) 639* 640* W := C**T * V**T = (C1**T * V1**T + C2**T * V2**T) (stored in WORK) 641* 642* W := C2**T 643* 644 DO 190 J = 1, K 645 CALL SCOPY( LASTC, C( LASTV-K+J, 1 ), LDC, 646 $ WORK( 1, J ), 1 ) 647 190 CONTINUE 648* 649* W := W * V2**T 650* 651 CALL STRMM( 'Right', 'Lower', 'Transpose', 'Unit', 652 $ LASTC, K, ONE, V( 1, LASTV-K+1 ), LDV, 653 $ WORK, LDWORK ) 654 IF( LASTV.GT.K ) THEN 655* 656* W := W + C1**T * V1**T 657* 658 CALL SGEMM( 'Transpose', 'Transpose', 659 $ LASTC, K, LASTV-K, ONE, C, LDC, V, LDV, 660 $ ONE, WORK, LDWORK ) 661 END IF 662* 663* W := W * T**T or W * T 664* 665 CALL STRMM( 'Right', 'Lower', TRANST, 'Non-unit', 666 $ LASTC, K, ONE, T, LDT, WORK, LDWORK ) 667* 668* C := C - V**T * W**T 669* 670 IF( LASTV.GT.K ) THEN 671* 672* C1 := C1 - V1**T * W**T 673* 674 CALL SGEMM( 'Transpose', 'Transpose', 675 $ LASTV-K, LASTC, K, -ONE, V, LDV, WORK, LDWORK, 676 $ ONE, C, LDC ) 677 END IF 678* 679* W := W * V2 680* 681 CALL STRMM( 'Right', 'Lower', 'No transpose', 'Unit', 682 $ LASTC, K, ONE, V( 1, LASTV-K+1 ), LDV, 683 $ WORK, LDWORK ) 684* 685* C2 := C2 - W**T 686* 687 DO 210 J = 1, K 688 DO 200 I = 1, LASTC 689 C( LASTV-K+J, I ) = C( LASTV-K+J, I ) - WORK(I, J) 690 200 CONTINUE 691 210 CONTINUE 692* 693 ELSE IF( LSAME( SIDE, 'R' ) ) THEN 694* 695* Form C * H or C * H**T where C = ( C1 C2 ) 696* 697 LASTV = MAX( K, ILASLC( K, N, V, LDV ) ) 698 LASTC = ILASLR( M, LASTV, C, LDC ) 699* 700* W := C * V**T = (C1*V1**T + C2*V2**T) (stored in WORK) 701* 702* W := C2 703* 704 DO 220 J = 1, K 705 CALL SCOPY( LASTC, C( 1, LASTV-K+J ), 1, 706 $ WORK( 1, J ), 1 ) 707 220 CONTINUE 708* 709* W := W * V2**T 710* 711 CALL STRMM( 'Right', 'Lower', 'Transpose', 'Unit', 712 $ LASTC, K, ONE, V( 1, LASTV-K+1 ), LDV, 713 $ WORK, LDWORK ) 714 IF( LASTV.GT.K ) THEN 715* 716* W := W + C1 * V1**T 717* 718 CALL SGEMM( 'No transpose', 'Transpose', 719 $ LASTC, K, LASTV-K, ONE, C, LDC, V, LDV, 720 $ ONE, WORK, LDWORK ) 721 END IF 722* 723* W := W * T or W * T**T 724* 725 CALL STRMM( 'Right', 'Lower', TRANS, 'Non-unit', 726 $ LASTC, K, ONE, T, LDT, WORK, LDWORK ) 727* 728* C := C - W * V 729* 730 IF( LASTV.GT.K ) THEN 731* 732* C1 := C1 - W * V1 733* 734 CALL SGEMM( 'No transpose', 'No transpose', 735 $ LASTC, LASTV-K, K, -ONE, WORK, LDWORK, V, LDV, 736 $ ONE, C, LDC ) 737 END IF 738* 739* W := W * V2 740* 741 CALL STRMM( 'Right', 'Lower', 'No transpose', 'Unit', 742 $ LASTC, K, ONE, V( 1, LASTV-K+1 ), LDV, 743 $ WORK, LDWORK ) 744* 745* C1 := C1 - W 746* 747 DO 240 J = 1, K 748 DO 230 I = 1, LASTC 749 C( I, LASTV-K+J ) = C( I, LASTV-K+J ) 750 $ - WORK( I, J ) 751 230 CONTINUE 752 240 CONTINUE 753* 754 END IF 755* 756 END IF 757 END IF 758* 759 RETURN 760* 761* End of SLARFB 762* 763 END 764