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MAN page from openSUSE Leap 42 blas-man-3.5.0-9.1.noarch.rpm
cherk.fSection: LAPACK (3) Updated: Fri Nov 4 2016 Index NAMEcherk.f - SYNOPSIS Functions/Subroutines
subroutine CHERK (UPLO, TRANS, N, K, ALPHA, A, LDA, BETA, C, LDC)
CHERK
Function/Subroutine Documentation subroutine CHERK (character UPLO, character TRANS, integer N, integer K, real ALPHA, complex, dimension(lda,*) A, integer LDA, real BETA, complex, dimension(ldc,*) C, integer LDC)CHERK Purpose: CHERK performs one of the hermitian rank k operations C := alpha*A*A**H + beta*C, or C := alpha*A**H*A + beta*C, where alpha and beta are real scalars, C is an n by n hermitian matrix and A is an n by k matrix in the first case and a k by n matrix in the second case.
Parameters: - UPLO
UPLO is CHARACTER*1 On entry, UPLO specifies whether the upper or lower triangular part of the array C is to be referenced as follows: UPLO = 'U' or 'u' Only the upper triangular part of C is to be referenced. UPLO = 'L' or 'l' Only the lower triangular part of C is to be referenced.
TRANS
TRANS is CHARACTER*1 On entry, TRANS specifies the operation to be performed as follows: TRANS = 'N' or 'n' C := alpha*A*A**H + beta*C. TRANS = 'C' or 'c' C := alpha*A**H*A + beta*C.
N
N is INTEGER On entry, N specifies the order of the matrix C. N must be at least zero.
K
K is INTEGER On entry with TRANS = 'N' or 'n', K specifies the number of columns of the matrix A, and on entry with TRANS = 'C' or 'c', K specifies the number of rows of the matrix A. K must be at least zero.
ALPHA
ALPHA is REAL On entry, ALPHA specifies the scalar alpha.
A
A is COMPLEX array of DIMENSION ( LDA, ka ), where ka is k when TRANS = 'N' or 'n', and is n otherwise. Before entry with TRANS = 'N' or 'n', the leading n by k part of the array A must contain the matrix A, otherwise the leading k by n part of the array A must contain the matrix A.
LDA
LDA is INTEGER On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. When TRANS = 'N' or 'n' then LDA must be at least max( 1, n ), otherwise LDA must be at least max( 1, k ).
BETA
BETA is REAL On entry, BETA specifies the scalar beta.
C
C is COMPLEX array of DIMENSION ( LDC, n ). Before entry with UPLO = 'U' or 'u', the leading n by n upper triangular part of the array C must contain the upper triangular part of the hermitian matrix and the strictly lower triangular part of C is not referenced. On exit, the upper triangular part of the array C is overwritten by the upper triangular part of the updated matrix. Before entry with UPLO = 'L' or 'l', the leading n by n lower triangular part of the array C must contain the lower triangular part of the hermitian matrix and the strictly upper triangular part of C is not referenced. On exit, the lower triangular part of the array C is overwritten by the lower triangular part of the updated matrix. Note that the imaginary parts of the diagonal elements need not be set, they are assumed to be zero, and on exit they are set to zero.
LDC
LDC is INTEGER On entry, LDC specifies the first dimension of C as declared in the calling (sub) program. LDC must be at least max( 1, n ).
Author: - Univ. of Tennessee
Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd.
Date: - November 2011
Further Details: Level 3 Blas routine. -- Written on 8-February-1989. Jack Dongarra, Argonne National Laboratory. Iain Duff, AERE Harwell. Jeremy Du Croz, Numerical Algorithms Group Ltd. Sven Hammarling, Numerical Algorithms Group Ltd. -- Modified 8-Nov-93 to set C(J,J) to REAL( C(J,J) ) when BETA = 1. Ed Anderson, Cray Research Inc.
Definition at line 175 of file cherk.f. 175 *176 * -- Reference BLAS level3 routine (version 3.4.0) --177 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --178 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--179 * November 2011180 *181 * .. Scalar Arguments ..182 REAL alpha,beta183 INTEGER k,lda,ldc,n184 CHARACTER trans,uplo185 * ..186 * .. Array Arguments ..187 COMPLEX a(lda,*),c(ldc,*)188 * ..189 *190 * =====================================================================191 *192 * .. External Functions ..193 LOGICAL lsame194 EXTERNAL lsame195 * ..196 * .. External Subroutines ..197 EXTERNAL xerbla198 * ..199 * .. Intrinsic Functions ..200 INTRINSIC cmplx,conjg,max,real201 * ..202 * .. Local Scalars ..203 COMPLEX temp204 REAL rtemp205 INTEGER i,info,j,l,nrowa206 LOGICAL upper207 * ..208 * .. Parameters ..209 REAL one,zero210 parameter(one=1.0e+0,zero=0.0e+0)211 * ..212 *213 * Test the input parameters.214 *215 IF (lsame(trans,'N')) THEN216 nrowa = n217 ELSE218 nrowa = k219 END IF220 upper = lsame(uplo,'U')221 *222 info = 0223 IF ((.NOT.upper) .AND. (.NOT.lsame(uplo,'L'))) THEN224 info = 1225 ELSE IF ((.NOT.lsame(trans,'N')) .AND.226 + (.NOT.lsame(trans,'C'))) THEN227 info = 2228 ELSE IF (n.LT.0) THEN229 info = 3230 ELSE IF (k.LT.0) THEN231 info = 4232 ELSE IF (lda.LT.max(1,nrowa)) THEN233 info = 7234 ELSE IF (ldc.LT.max(1,n)) THEN235 info = 10236 END IF237 IF (info.NE.0) THEN238 CALL xerbla('CHERK ',info)239 RETURN240 END IF241 *242 * Quick return if possible.243 *244 IF ((n.EQ.0) .OR. (((alpha.EQ.zero).OR.245 + (k.EQ.0)).AND. (beta.EQ.one))) RETURN246 *247 * And when alpha.eq.zero.248 *249 IF (alpha.EQ.zero) THEN250 IF (upper) THEN251 IF (beta.EQ.zero) THEN252 DO 20 j = 1,n253 DO 10 i = 1,j254 c(i,j) = zero255 10 CONTINUE256 20 CONTINUE257 ELSE258 DO 40 j = 1,n259 DO 30 i = 1,j - 1260 c(i,j) = beta*c(i,j)261 30 CONTINUE262 c(j,j) = beta*REAL(c(j,j))263 40 CONTINUE264 END IF265 ELSE266 IF (beta.EQ.zero) THEN267 DO 60 j = 1,n268 DO 50 i = j,n269 c(i,j) = zero270 50 CONTINUE271 60 CONTINUE272 ELSE273 DO 80 j = 1,n274 c(j,j) = beta*REAL(c(j,j))275 DO 70 i = j + 1,n276 c(i,j) = beta*c(i,j)277 70 CONTINUE278 80 CONTINUE279 END IF280 END IF281 RETURN282 END IF283 *284 * Start the operations.285 *286 IF (lsame(trans,'N')) THEN287 *288 * Form C := alpha*A*A**H + beta*C.289 *290 IF (upper) THEN291 DO 130 j = 1,n292 IF (beta.EQ.zero) THEN293 DO 90 i = 1,j294 c(i,j) = zero295 90 CONTINUE296 ELSE IF (beta.NE.one) THEN297 DO 100 i = 1,j - 1298 c(i,j) = beta*c(i,j)299 100 CONTINUE300 c(j,j) = beta*REAL(c(j,j))301 ELSE302 c(j,j) = REAL(c(j,j))303 END IF304 DO 120 l = 1,k305 IF (a(j,l).NE.cmplx(zero)) THEN306 temp = alpha*conjg(a(j,l))307 DO 110 i = 1,j - 1308 c(i,j) = c(i,j) + temp*a(i,l)309 110 CONTINUE310 c(j,j) = REAL(C(J,J)) + REAL(temp*a(i,l))311 END IF312 120 CONTINUE313 130 CONTINUE314 ELSE315 DO 180 j = 1,n316 IF (beta.EQ.zero) THEN317 DO 140 i = j,n318 c(i,j) = zero319 140 CONTINUE320 ELSE IF (beta.NE.one) THEN321 c(j,j) = beta*REAL(c(j,j))322 DO 150 i = j + 1,n323 c(i,j) = beta*c(i,j)324 150 CONTINUE325 ELSE326 c(j,j) = REAL(c(j,j))327 END IF328 DO 170 l = 1,k329 IF (a(j,l).NE.cmplx(zero)) THEN330 temp = alpha*conjg(a(j,l))331 c(j,j) = REAL(C(J,J)) + REAL(temp*a(j,l))332 DO 160 i = j + 1,n333 c(i,j) = c(i,j) + temp*a(i,l)334 160 CONTINUE335 END IF336 170 CONTINUE337 180 CONTINUE338 END IF339 ELSE340 *341 * Form C := alpha*A**H*A + beta*C.342 *343 IF (upper) THEN344 DO 220 j = 1,n345 DO 200 i = 1,j - 1346 temp = zero347 DO 190 l = 1,k348 temp = temp + conjg(a(l,i))*a(l,j)349 190 CONTINUE350 IF (beta.EQ.zero) THEN351 c(i,j) = alpha*temp352 ELSE353 c(i,j) = alpha*temp + beta*c(i,j)354 END IF355 200 CONTINUE356 rtemp = zero357 DO 210 l = 1,k358 rtemp = rtemp + conjg(a(l,j))*a(l,j)359 210 CONTINUE360 IF (beta.EQ.zero) THEN361 c(j,j) = alpha*rtemp362 ELSE363 c(j,j) = alpha*rtemp + beta*REAL(c(j,j))364 END IF365 220 CONTINUE366 ELSE367 DO 260 j = 1,n368 rtemp = zero369 DO 230 l = 1,k370 rtemp = rtemp + conjg(a(l,j))*a(l,j)371 230 CONTINUE372 IF (beta.EQ.zero) THEN373 c(j,j) = alpha*rtemp374 ELSE375 c(j,j) = alpha*rtemp + beta*REAL(c(j,j))376 END IF377 DO 250 i = j + 1,n378 temp = zero379 DO 240 l = 1,k380 temp = temp + conjg(a(l,i))*a(l,j)381 240 CONTINUE382 IF (beta.EQ.zero) THEN383 c(i,j) = alpha*temp384 ELSE385 c(i,j) = alpha*temp + beta*c(i,j)386 END IF387 250 CONTINUE388 260 CONTINUE389 END IF390 END IF391 *392 RETURN393 *394 * End of CHERK .395 * AuthorGenerated automatically by Doxygen for LAPACK from the source code.
Index- NAME
- SYNOPSIS
- Functions/Subroutines
- Function/Subroutine Documentation
- subroutine CHERK (character UPLO, character TRANS, integer N, integer K, real ALPHA, complex, dimension(lda,*) A, integer LDA, real BETA, complex, dimension(ldc,*) C, integer LDC)
- Author
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