 |
LAPACK 3.3.1
Linear Algebra PACKage
|
|
LAPACK 3.3.1
Linear Algebra PACKage
|
00001 SUBROUTINE ZLASYF( UPLO, N, NB, KB, A, LDA, IPIV, W, LDW, INFO ) 00002 * 00003 * -- LAPACK routine (version 3.3.1) -- 00004 * -- LAPACK is a software package provided by Univ. of Tennessee, -- 00005 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- 00006 * -- April 2011 -- 00007 * 00008 * .. Scalar Arguments .. 00009 CHARACTER UPLO 00010 INTEGER INFO, KB, LDA, LDW, N, NB 00011 * .. 00012 * .. Array Arguments .. 00013 INTEGER IPIV( * ) 00014 COMPLEX*16 A( LDA, * ), W( LDW, * ) 00015 * .. 00016 * 00017 * Purpose 00018 * ======= 00019 * 00020 * ZLASYF computes a partial factorization of a complex symmetric matrix 00021 * A using the Bunch-Kaufman diagonal pivoting method. The partial 00022 * factorization has the form: 00023 * 00024 * A = ( I U12 ) ( A11 0 ) ( I 0 ) if UPLO = 'U', or: 00025 * ( 0 U22 ) ( 0 D ) ( U12**T U22**T ) 00026 * 00027 * A = ( L11 0 ) ( D 0 ) ( L11**T L21**T ) if UPLO = 'L' 00028 * ( L21 I ) ( 0 A22 ) ( 0 I ) 00029 * 00030 * where the order of D is at most NB. The actual order is returned in 00031 * the argument KB, and is either NB or NB-1, or N if N <= NB. 00032 * Note that U**T denotes the transpose of U. 00033 * 00034 * ZLASYF is an auxiliary routine called by ZSYTRF. It uses blocked code 00035 * (calling Level 3 BLAS) to update the submatrix A11 (if UPLO = 'U') or 00036 * A22 (if UPLO = 'L'). 00037 * 00038 * Arguments 00039 * ========= 00040 * 00041 * UPLO (input) CHARACTER*1 00042 * Specifies whether the upper or lower triangular part of the 00043 * symmetric matrix A is stored: 00044 * = 'U': Upper triangular 00045 * = 'L': Lower triangular 00046 * 00047 * N (input) INTEGER 00048 * The order of the matrix A. N >= 0. 00049 * 00050 * NB (input) INTEGER 00051 * The maximum number of columns of the matrix A that should be 00052 * factored. NB should be at least 2 to allow for 2-by-2 pivot 00053 * blocks. 00054 * 00055 * KB (output) INTEGER 00056 * The number of columns of A that were actually factored. 00057 * KB is either NB-1 or NB, or N if N <= NB. 00058 * 00059 * A (input/output) COMPLEX*16 array, dimension (LDA,N) 00060 * On entry, the symmetric matrix A. If UPLO = 'U', the leading 00061 * n-by-n upper triangular part of A contains the upper 00062 * triangular part of the matrix A, and the strictly lower 00063 * triangular part of A is not referenced. If UPLO = 'L', the 00064 * leading n-by-n lower triangular part of A contains the lower 00065 * triangular part of the matrix A, and the strictly upper 00066 * triangular part of A is not referenced. 00067 * On exit, A contains details of the partial factorization. 00068 * 00069 * LDA (input) INTEGER 00070 * The leading dimension of the array A. LDA >= max(1,N). 00071 * 00072 * IPIV (output) INTEGER array, dimension (N) 00073 * Details of the interchanges and the block structure of D. 00074 * If UPLO = 'U', only the last KB elements of IPIV are set; 00075 * if UPLO = 'L', only the first KB elements are set. 00076 * 00077 * If IPIV(k) > 0, then rows and columns k and IPIV(k) were 00078 * interchanged and D(k,k) is a 1-by-1 diagonal block. 00079 * If UPLO = 'U' and IPIV(k) = IPIV(k-1) < 0, then rows and 00080 * columns k-1 and -IPIV(k) were interchanged and D(k-1:k,k-1:k) 00081 * is a 2-by-2 diagonal block. If UPLO = 'L' and IPIV(k) = 00082 * IPIV(k+1) < 0, then rows and columns k+1 and -IPIV(k) were 00083 * interchanged and D(k:k+1,k:k+1) is a 2-by-2 diagonal block. 00084 * 00085 * W (workspace) COMPLEX*16 array, dimension (LDW,NB) 00086 * 00087 * LDW (input) INTEGER 00088 * The leading dimension of the array W. LDW >= max(1,N). 00089 * 00090 * INFO (output) INTEGER 00091 * = 0: successful exit 00092 * > 0: if INFO = k, D(k,k) is exactly zero. The factorization 00093 * has been completed, but the block diagonal matrix D is 00094 * exactly singular. 00095 * 00096 * ===================================================================== 00097 * 00098 * .. Parameters .. 00099 DOUBLE PRECISION ZERO, ONE 00100 PARAMETER ( ZERO = 0.0D+0, ONE = 1.0D+0 ) 00101 DOUBLE PRECISION EIGHT, SEVTEN 00102 PARAMETER ( EIGHT = 8.0D+0, SEVTEN = 17.0D+0 ) 00103 COMPLEX*16 CONE 00104 PARAMETER ( CONE = ( 1.0D+0, 0.0D+0 ) ) 00105 * .. 00106 * .. Local Scalars .. 00107 INTEGER IMAX, J, JB, JJ, JMAX, JP, K, KK, KKW, KP, 00108 $ KSTEP, KW 00109 DOUBLE PRECISION ABSAKK, ALPHA, COLMAX, ROWMAX 00110 COMPLEX*16 D11, D21, D22, R1, T, Z 00111 * .. 00112 * .. External Functions .. 00113 LOGICAL LSAME 00114 INTEGER IZAMAX 00115 EXTERNAL LSAME, IZAMAX 00116 * .. 00117 * .. External Subroutines .. 00118 EXTERNAL ZCOPY, ZGEMM, ZGEMV, ZSCAL, ZSWAP 00119 * .. 00120 * .. Intrinsic Functions .. 00121 INTRINSIC ABS, DBLE, DIMAG, MAX, MIN, SQRT 00122 * .. 00123 * .. Statement Functions .. 00124 DOUBLE PRECISION CABS1 00125 * .. 00126 * .. Statement Function definitions .. 00127 CABS1( Z ) = ABS( DBLE( Z ) ) + ABS( DIMAG( Z ) ) 00128 * .. 00129 * .. Executable Statements .. 00130 * 00131 INFO = 0 00132 * 00133 * Initialize ALPHA for use in choosing pivot block size. 00134 * 00135 ALPHA = ( ONE+SQRT( SEVTEN ) ) / EIGHT 00136 * 00137 IF( LSAME( UPLO, 'U' ) ) THEN 00138 * 00139 * Factorize the trailing columns of A using the upper triangle 00140 * of A and working backwards, and compute the matrix W = U12*D 00141 * for use in updating A11 00142 * 00143 * K is the main loop index, decreasing from N in steps of 1 or 2 00144 * 00145 * KW is the column of W which corresponds to column K of A 00146 * 00147 K = N 00148 10 CONTINUE 00149 KW = NB + K - N 00150 * 00151 * Exit from loop 00152 * 00153 IF( ( K.LE.N-NB+1 .AND. NB.LT.N ) .OR. K.LT.1 ) 00154 $ GO TO 30 00155 * 00156 * Copy column K of A to column KW of W and update it 00157 * 00158 CALL ZCOPY( K, A( 1, K ), 1, W( 1, KW ), 1 ) 00159 IF( K.LT.N ) 00160 $ CALL ZGEMV( 'No transpose', K, N-K, -CONE, A( 1, K+1 ), LDA, 00161 $ W( K, KW+1 ), LDW, CONE, W( 1, KW ), 1 ) 00162 * 00163 KSTEP = 1 00164 * 00165 * Determine rows and columns to be interchanged and whether 00166 * a 1-by-1 or 2-by-2 pivot block will be used 00167 * 00168 ABSAKK = CABS1( W( K, KW ) ) 00169 * 00170 * IMAX is the row-index of the largest off-diagonal element in 00171 * column K, and COLMAX is its absolute value 00172 * 00173 IF( K.GT.1 ) THEN 00174 IMAX = IZAMAX( K-1, W( 1, KW ), 1 ) 00175 COLMAX = CABS1( W( IMAX, KW ) ) 00176 ELSE 00177 COLMAX = ZERO 00178 END IF 00179 * 00180 IF( MAX( ABSAKK, COLMAX ).EQ.ZERO ) THEN 00181 * 00182 * Column K is zero: set INFO and continue 00183 * 00184 IF( INFO.EQ.0 ) 00185 $ INFO = K 00186 KP = K 00187 ELSE 00188 IF( ABSAKK.GE.ALPHA*COLMAX ) THEN 00189 * 00190 * no interchange, use 1-by-1 pivot block 00191 * 00192 KP = K 00193 ELSE 00194 * 00195 * Copy column IMAX to column KW-1 of W and update it 00196 * 00197 CALL ZCOPY( IMAX, A( 1, IMAX ), 1, W( 1, KW-1 ), 1 ) 00198 CALL ZCOPY( K-IMAX, A( IMAX, IMAX+1 ), LDA, 00199 $ W( IMAX+1, KW-1 ), 1 ) 00200 IF( K.LT.N ) 00201 $ CALL ZGEMV( 'No transpose', K, N-K, -CONE, 00202 $ A( 1, K+1 ), LDA, W( IMAX, KW+1 ), LDW, 00203 $ CONE, W( 1, KW-1 ), 1 ) 00204 * 00205 * JMAX is the column-index of the largest off-diagonal 00206 * element in row IMAX, and ROWMAX is its absolute value 00207 * 00208 JMAX = IMAX + IZAMAX( K-IMAX, W( IMAX+1, KW-1 ), 1 ) 00209 ROWMAX = CABS1( W( JMAX, KW-1 ) ) 00210 IF( IMAX.GT.1 ) THEN 00211 JMAX = IZAMAX( IMAX-1, W( 1, KW-1 ), 1 ) 00212 ROWMAX = MAX( ROWMAX, CABS1( W( JMAX, KW-1 ) ) ) 00213 END IF 00214 * 00215 IF( ABSAKK.GE.ALPHA*COLMAX*( COLMAX / ROWMAX ) ) THEN 00216 * 00217 * no interchange, use 1-by-1 pivot block 00218 * 00219 KP = K 00220 ELSE IF( CABS1( W( IMAX, KW-1 ) ).GE.ALPHA*ROWMAX ) THEN 00221 * 00222 * interchange rows and columns K and IMAX, use 1-by-1 00223 * pivot block 00224 * 00225 KP = IMAX 00226 * 00227 * copy column KW-1 of W to column KW 00228 * 00229 CALL ZCOPY( K, W( 1, KW-1 ), 1, W( 1, KW ), 1 ) 00230 ELSE 00231 * 00232 * interchange rows and columns K-1 and IMAX, use 2-by-2 00233 * pivot block 00234 * 00235 KP = IMAX 00236 KSTEP = 2 00237 END IF 00238 END IF 00239 * 00240 KK = K - KSTEP + 1 00241 KKW = NB + KK - N 00242 * 00243 * Updated column KP is already stored in column KKW of W 00244 * 00245 IF( KP.NE.KK ) THEN 00246 * 00247 * Copy non-updated column KK to column KP 00248 * 00249 A( KP, K ) = A( KK, K ) 00250 CALL ZCOPY( K-1-KP, A( KP+1, KK ), 1, A( KP, KP+1 ), 00251 $ LDA ) 00252 CALL ZCOPY( KP, A( 1, KK ), 1, A( 1, KP ), 1 ) 00253 * 00254 * Interchange rows KK and KP in last KK columns of A and W 00255 * 00256 CALL ZSWAP( N-KK+1, A( KK, KK ), LDA, A( KP, KK ), LDA ) 00257 CALL ZSWAP( N-KK+1, W( KK, KKW ), LDW, W( KP, KKW ), 00258 $ LDW ) 00259 END IF 00260 * 00261 IF( KSTEP.EQ.1 ) THEN 00262 * 00263 * 1-by-1 pivot block D(k): column KW of W now holds 00264 * 00265 * W(k) = U(k)*D(k) 00266 * 00267 * where U(k) is the k-th column of U 00268 * 00269 * Store U(k) in column k of A 00270 * 00271 CALL ZCOPY( K, W( 1, KW ), 1, A( 1, K ), 1 ) 00272 R1 = CONE / A( K, K ) 00273 CALL ZSCAL( K-1, R1, A( 1, K ), 1 ) 00274 ELSE 00275 * 00276 * 2-by-2 pivot block D(k): columns KW and KW-1 of W now 00277 * hold 00278 * 00279 * ( W(k-1) W(k) ) = ( U(k-1) U(k) )*D(k) 00280 * 00281 * where U(k) and U(k-1) are the k-th and (k-1)-th columns 00282 * of U 00283 * 00284 IF( K.GT.2 ) THEN 00285 * 00286 * Store U(k) and U(k-1) in columns k and k-1 of A 00287 * 00288 D21 = W( K-1, KW ) 00289 D11 = W( K, KW ) / D21 00290 D22 = W( K-1, KW-1 ) / D21 00291 T = CONE / ( D11*D22-CONE ) 00292 D21 = T / D21 00293 DO 20 J = 1, K - 2 00294 A( J, K-1 ) = D21*( D11*W( J, KW-1 )-W( J, KW ) ) 00295 A( J, K ) = D21*( D22*W( J, KW )-W( J, KW-1 ) ) 00296 20 CONTINUE 00297 END IF 00298 * 00299 * Copy D(k) to A 00300 * 00301 A( K-1, K-1 ) = W( K-1, KW-1 ) 00302 A( K-1, K ) = W( K-1, KW ) 00303 A( K, K ) = W( K, KW ) 00304 END IF 00305 END IF 00306 * 00307 * Store details of the interchanges in IPIV 00308 * 00309 IF( KSTEP.EQ.1 ) THEN 00310 IPIV( K ) = KP 00311 ELSE 00312 IPIV( K ) = -KP 00313 IPIV( K-1 ) = -KP 00314 END IF 00315 * 00316 * Decrease K and return to the start of the main loop 00317 * 00318 K = K - KSTEP 00319 GO TO 10 00320 * 00321 30 CONTINUE 00322 * 00323 * Update the upper triangle of A11 (= A(1:k,1:k)) as 00324 * 00325 * A11 := A11 - U12*D*U12**T = A11 - U12*W**T 00326 * 00327 * computing blocks of NB columns at a time 00328 * 00329 DO 50 J = ( ( K-1 ) / NB )*NB + 1, 1, -NB 00330 JB = MIN( NB, K-J+1 ) 00331 * 00332 * Update the upper triangle of the diagonal block 00333 * 00334 DO 40 JJ = J, J + JB - 1 00335 CALL ZGEMV( 'No transpose', JJ-J+1, N-K, -CONE, 00336 $ A( J, K+1 ), LDA, W( JJ, KW+1 ), LDW, CONE, 00337 $ A( J, JJ ), 1 ) 00338 40 CONTINUE 00339 * 00340 * Update the rectangular superdiagonal block 00341 * 00342 CALL ZGEMM( 'No transpose', 'Transpose', J-1, JB, N-K, 00343 $ -CONE, A( 1, K+1 ), LDA, W( J, KW+1 ), LDW, 00344 $ CONE, A( 1, J ), LDA ) 00345 50 CONTINUE 00346 * 00347 * Put U12 in standard form by partially undoing the interchanges 00348 * in columns k+1:n 00349 * 00350 J = K + 1 00351 60 CONTINUE 00352 JJ = J 00353 JP = IPIV( J ) 00354 IF( JP.LT.0 ) THEN 00355 JP = -JP 00356 J = J + 1 00357 END IF 00358 J = J + 1 00359 IF( JP.NE.JJ .AND. J.LE.N ) 00360 $ CALL ZSWAP( N-J+1, A( JP, J ), LDA, A( JJ, J ), LDA ) 00361 IF( J.LE.N ) 00362 $ GO TO 60 00363 * 00364 * Set KB to the number of columns factorized 00365 * 00366 KB = N - K 00367 * 00368 ELSE 00369 * 00370 * Factorize the leading columns of A using the lower triangle 00371 * of A and working forwards, and compute the matrix W = L21*D 00372 * for use in updating A22 00373 * 00374 * K is the main loop index, increasing from 1 in steps of 1 or 2 00375 * 00376 K = 1 00377 70 CONTINUE 00378 * 00379 * Exit from loop 00380 * 00381 IF( ( K.GE.NB .AND. NB.LT.N ) .OR. K.GT.N ) 00382 $ GO TO 90 00383 * 00384 * Copy column K of A to column K of W and update it 00385 * 00386 CALL ZCOPY( N-K+1, A( K, K ), 1, W( K, K ), 1 ) 00387 CALL ZGEMV( 'No transpose', N-K+1, K-1, -CONE, A( K, 1 ), LDA, 00388 $ W( K, 1 ), LDW, CONE, W( K, K ), 1 ) 00389 * 00390 KSTEP = 1 00391 * 00392 * Determine rows and columns to be interchanged and whether 00393 * a 1-by-1 or 2-by-2 pivot block will be used 00394 * 00395 ABSAKK = CABS1( W( K, K ) ) 00396 * 00397 * IMAX is the row-index of the largest off-diagonal element in 00398 * column K, and COLMAX is its absolute value 00399 * 00400 IF( K.LT.N ) THEN 00401 IMAX = K + IZAMAX( N-K, W( K+1, K ), 1 ) 00402 COLMAX = CABS1( W( IMAX, K ) ) 00403 ELSE 00404 COLMAX = ZERO 00405 END IF 00406 * 00407 IF( MAX( ABSAKK, COLMAX ).EQ.ZERO ) THEN 00408 * 00409 * Column K is zero: set INFO and continue 00410 * 00411 IF( INFO.EQ.0 ) 00412 $ INFO = K 00413 KP = K 00414 ELSE 00415 IF( ABSAKK.GE.ALPHA*COLMAX ) THEN 00416 * 00417 * no interchange, use 1-by-1 pivot block 00418 * 00419 KP = K 00420 ELSE 00421 * 00422 * Copy column IMAX to column K+1 of W and update it 00423 * 00424 CALL ZCOPY( IMAX-K, A( IMAX, K ), LDA, W( K, K+1 ), 1 ) 00425 CALL ZCOPY( N-IMAX+1, A( IMAX, IMAX ), 1, W( IMAX, K+1 ), 00426 $ 1 ) 00427 CALL ZGEMV( 'No transpose', N-K+1, K-1, -CONE, A( K, 1 ), 00428 $ LDA, W( IMAX, 1 ), LDW, CONE, W( K, K+1 ), 00429 $ 1 ) 00430 * 00431 * JMAX is the column-index of the largest off-diagonal 00432 * element in row IMAX, and ROWMAX is its absolute value 00433 * 00434 JMAX = K - 1 + IZAMAX( IMAX-K, W( K, K+1 ), 1 ) 00435 ROWMAX = CABS1( W( JMAX, K+1 ) ) 00436 IF( IMAX.LT.N ) THEN 00437 JMAX = IMAX + IZAMAX( N-IMAX, W( IMAX+1, K+1 ), 1 ) 00438 ROWMAX = MAX( ROWMAX, CABS1( W( JMAX, K+1 ) ) ) 00439 END IF 00440 * 00441 IF( ABSAKK.GE.ALPHA*COLMAX*( COLMAX / ROWMAX ) ) THEN 00442 * 00443 * no interchange, use 1-by-1 pivot block 00444 * 00445 KP = K 00446 ELSE IF( CABS1( W( IMAX, K+1 ) ).GE.ALPHA*ROWMAX ) THEN 00447 * 00448 * interchange rows and columns K and IMAX, use 1-by-1 00449 * pivot block 00450 * 00451 KP = IMAX 00452 * 00453 * copy column K+1 of W to column K 00454 * 00455 CALL ZCOPY( N-K+1, W( K, K+1 ), 1, W( K, K ), 1 ) 00456 ELSE 00457 * 00458 * interchange rows and columns K+1 and IMAX, use 2-by-2 00459 * pivot block 00460 * 00461 KP = IMAX 00462 KSTEP = 2 00463 END IF 00464 END IF 00465 * 00466 KK = K + KSTEP - 1 00467 * 00468 * Updated column KP is already stored in column KK of W 00469 * 00470 IF( KP.NE.KK ) THEN 00471 * 00472 * Copy non-updated column KK to column KP 00473 * 00474 A( KP, K ) = A( KK, K ) 00475 CALL ZCOPY( KP-K-1, A( K+1, KK ), 1, A( KP, K+1 ), LDA ) 00476 CALL ZCOPY( N-KP+1, A( KP, KK ), 1, A( KP, KP ), 1 ) 00477 * 00478 * Interchange rows KK and KP in first KK columns of A and W 00479 * 00480 CALL ZSWAP( KK, A( KK, 1 ), LDA, A( KP, 1 ), LDA ) 00481 CALL ZSWAP( KK, W( KK, 1 ), LDW, W( KP, 1 ), LDW ) 00482 END IF 00483 * 00484 IF( KSTEP.EQ.1 ) THEN 00485 * 00486 * 1-by-1 pivot block D(k): column k of W now holds 00487 * 00488 * W(k) = L(k)*D(k) 00489 * 00490 * where L(k) is the k-th column of L 00491 * 00492 * Store L(k) in column k of A 00493 * 00494 CALL ZCOPY( N-K+1, W( K, K ), 1, A( K, K ), 1 ) 00495 IF( K.LT.N ) THEN 00496 R1 = CONE / A( K, K ) 00497 CALL ZSCAL( N-K, R1, A( K+1, K ), 1 ) 00498 END IF 00499 ELSE 00500 * 00501 * 2-by-2 pivot block D(k): columns k and k+1 of W now hold 00502 * 00503 * ( W(k) W(k+1) ) = ( L(k) L(k+1) )*D(k) 00504 * 00505 * where L(k) and L(k+1) are the k-th and (k+1)-th columns 00506 * of L 00507 * 00508 IF( K.LT.N-1 ) THEN 00509 * 00510 * Store L(k) and L(k+1) in columns k and k+1 of A 00511 * 00512 D21 = W( K+1, K ) 00513 D11 = W( K+1, K+1 ) / D21 00514 D22 = W( K, K ) / D21 00515 T = CONE / ( D11*D22-CONE ) 00516 D21 = T / D21 00517 DO 80 J = K + 2, N 00518 A( J, K ) = D21*( D11*W( J, K )-W( J, K+1 ) ) 00519 A( J, K+1 ) = D21*( D22*W( J, K+1 )-W( J, K ) ) 00520 80 CONTINUE 00521 END IF 00522 * 00523 * Copy D(k) to A 00524 * 00525 A( K, K ) = W( K, K ) 00526 A( K+1, K ) = W( K+1, K ) 00527 A( K+1, K+1 ) = W( K+1, K+1 ) 00528 END IF 00529 END IF 00530 * 00531 * Store details of the interchanges in IPIV 00532 * 00533 IF( KSTEP.EQ.1 ) THEN 00534 IPIV( K ) = KP 00535 ELSE 00536 IPIV( K ) = -KP 00537 IPIV( K+1 ) = -KP 00538 END IF 00539 * 00540 * Increase K and return to the start of the main loop 00541 * 00542 K = K + KSTEP 00543 GO TO 70 00544 * 00545 90 CONTINUE 00546 * 00547 * Update the lower triangle of A22 (= A(k:n,k:n)) as 00548 * 00549 * A22 := A22 - L21*D*L21**T = A22 - L21*W**T 00550 * 00551 * computing blocks of NB columns at a time 00552 * 00553 DO 110 J = K, N, NB 00554 JB = MIN( NB, N-J+1 ) 00555 * 00556 * Update the lower triangle of the diagonal block 00557 * 00558 DO 100 JJ = J, J + JB - 1 00559 CALL ZGEMV( 'No transpose', J+JB-JJ, K-1, -CONE, 00560 $ A( JJ, 1 ), LDA, W( JJ, 1 ), LDW, CONE, 00561 $ A( JJ, JJ ), 1 ) 00562 100 CONTINUE 00563 * 00564 * Update the rectangular subdiagonal block 00565 * 00566 IF( J+JB.LE.N ) 00567 $ CALL ZGEMM( 'No transpose', 'Transpose', N-J-JB+1, JB, 00568 $ K-1, -CONE, A( J+JB, 1 ), LDA, W( J, 1 ), 00569 $ LDW, CONE, A( J+JB, J ), LDA ) 00570 110 CONTINUE 00571 * 00572 * Put L21 in standard form by partially undoing the interchanges 00573 * in columns 1:k-1 00574 * 00575 J = K - 1 00576 120 CONTINUE 00577 JJ = J 00578 JP = IPIV( J ) 00579 IF( JP.LT.0 ) THEN 00580 JP = -JP 00581 J = J - 1 00582 END IF 00583 J = J - 1 00584 IF( JP.NE.JJ .AND. J.GE.1 ) 00585 $ CALL ZSWAP( J, A( JP, 1 ), LDA, A( JJ, 1 ), LDA ) 00586 IF( J.GE.1 ) 00587 $ GO TO 120 00588 * 00589 * Set KB to the number of columns factorized 00590 * 00591 KB = K - 1 00592 * 00593 END IF 00594 RETURN 00595 * 00596 * End of ZLASYF 00597 * 00598 END
1.7.3 
