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MAN page from openSUSE Leap 42 blas-man-3.5.0-9.1.noarch.rpm
chpr2.fSection: LAPACK (3) Updated: Fri Nov 4 2016 Index NAMEchpr2.f - SYNOPSIS Functions/Subroutines
subroutine CHPR2 (UPLO, N, ALPHA, X, INCX, Y, INCY, AP)
CHPR2
Function/Subroutine Documentation subroutine CHPR2 (character UPLO, integer N, complex ALPHA, complex, dimension(*) X, integer INCX, complex, dimension(*) Y, integer INCY, complex, dimension(*) AP)CHPR2 Purpose: CHPR2 performs the hermitian rank 2 operation A := alpha*x*y**H + conjg( alpha )*y*x**H + A, where alpha is a scalar, x and y are n element vectors and A is an n by n hermitian matrix, supplied in packed form.
Parameters: - UPLO
UPLO is CHARACTER*1 On entry, UPLO specifies whether the upper or lower triangular part of the matrix A is supplied in the packed array AP as follows: UPLO = 'U' or 'u' The upper triangular part of A is supplied in AP. UPLO = 'L' or 'l' The lower triangular part of A is supplied in AP.
N
N is INTEGER On entry, N specifies the order of the matrix A. N must be at least zero.
ALPHA
ALPHA is COMPLEX On entry, ALPHA specifies the scalar alpha.
X
X is COMPLEX array of dimension at least ( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented array X must contain the n element vector x.
INCX
INCX is INTEGER On entry, INCX specifies the increment for the elements of X. INCX must not be zero.
Y
Y is COMPLEX array of dimension at least ( 1 + ( n - 1 )*abs( INCY ) ). Before entry, the incremented array Y must contain the n element vector y.
INCY
INCY is INTEGER On entry, INCY specifies the increment for the elements of Y. INCY must not be zero.
AP
AP is COMPLEX array of DIMENSION at least ( ( n*( n + 1 ) )/2 ). Before entry with UPLO = 'U' or 'u', the array AP must contain the upper triangular part of the hermitian matrix packed sequentially, column by column, so that AP( 1 ) contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 ) and a( 2, 2 ) respectively, and so on. On exit, the array AP is overwritten by the upper triangular part of the updated matrix. Before entry with UPLO = 'L' or 'l', the array AP must contain the lower triangular part of the hermitian matrix packed sequentially, column by column, so that AP( 1 ) contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 ) and a( 3, 1 ) respectively, and so on. On exit, the array AP 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.
Author: - Univ. of Tennessee
Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd.
Date: - November 2011
Further Details: Level 2 Blas routine. -- Written on 22-October-1986. Jack Dongarra, Argonne National Lab. Jeremy Du Croz, Nag Central Office. Sven Hammarling, Nag Central Office. Richard Hanson, Sandia National Labs.
Definition at line 147 of file chpr2.f. 147 *148 * -- Reference BLAS level2 routine (version 3.4.0) --149 * -- Reference BLAS is a software package provided by Univ. of Tennessee, --150 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--151 * November 2011152 *153 * .. Scalar Arguments ..154 COMPLEX alpha155 INTEGER incx,incy,n156 CHARACTER uplo157 * ..158 * .. Array Arguments ..159 COMPLEX ap(*),x(*),y(*)160 * ..161 *162 * =====================================================================163 *164 * .. Parameters ..165 COMPLEX zero166 parameter(zero= (0.0e+0,0.0e+0))167 * ..168 * .. Local Scalars ..169 COMPLEX temp1,temp2170 INTEGER i,info,ix,iy,j,jx,jy,k,kk,kx,ky171 * ..172 * .. External Functions ..173 LOGICAL lsame174 EXTERNAL lsame175 * ..176 * .. External Subroutines ..177 EXTERNAL xerbla178 * ..179 * .. Intrinsic Functions ..180 INTRINSIC conjg,real181 * ..182 *183 * Test the input parameters.184 *185 info = 0186 IF (.NOT.lsame(uplo,'U') .AND. .NOT.lsame(uplo,'L')) THEN187 info = 1188 ELSE IF (n.LT.0) THEN189 info = 2190 ELSE IF (incx.EQ.0) THEN191 info = 5192 ELSE IF (incy.EQ.0) THEN193 info = 7194 END IF195 IF (info.NE.0) THEN196 CALL xerbla('CHPR2 ',info)197 RETURN198 END IF199 *200 * Quick return if possible.201 *202 IF ((n.EQ.0) .OR. (alpha.EQ.zero)) RETURN203 *204 * Set up the start points in X and Y if the increments are not both205 * unity.206 *207 IF ((incx.NE.1) .OR. (incy.NE.1)) THEN208 IF (incx.GT.0) THEN209 kx = 1210 ELSE211 kx = 1 - (n-1)*incx212 END IF213 IF (incy.GT.0) THEN214 ky = 1215 ELSE216 ky = 1 - (n-1)*incy217 END IF218 jx = kx219 jy = ky220 END IF221 *222 * Start the operations. In this version the elements of the array AP223 * are accessed sequentially with one pass through AP.224 *225 kk = 1226 IF (lsame(uplo,'U')) THEN227 *228 * Form A when upper triangle is stored in AP.229 *230 IF ((incx.EQ.1) .AND. (incy.EQ.1)) THEN231 DO 20 j = 1,n232 IF ((x(j).NE.zero) .OR. (y(j).NE.zero)) THEN233 temp1 = alpha*conjg(y(j))234 temp2 = conjg(alpha*x(j))235 k = kk236 DO 10 i = 1,j - 1237 ap(k) = ap(k) + x(i)*temp1 + y(i)*temp2238 k = k + 1239 10 CONTINUE240 ap(kk+j-1) = REAL(AP(KK+J-1)) +241 + REAL(x(j)*temp1+y(j)*temp2)242 ELSE243 ap(kk+j-1) = REAL(ap(kk+j-1))244 END IF245 kk = kk + j246 20 CONTINUE247 ELSE248 DO 40 j = 1,n249 IF ((x(jx).NE.zero) .OR. (y(jy).NE.zero)) THEN250 temp1 = alpha*conjg(y(jy))251 temp2 = conjg(alpha*x(jx))252 ix = kx253 iy = ky254 DO 30 k = kk,kk + j - 2255 ap(k) = ap(k) + x(ix)*temp1 + y(iy)*temp2256 ix = ix + incx257 iy = iy + incy258 30 CONTINUE259 ap(kk+j-1) = REAL(AP(KK+J-1)) +260 + REAL(x(jx)*temp1+y(jy)*temp2)261 ELSE262 ap(kk+j-1) = REAL(ap(kk+j-1))263 END IF264 jx = jx + incx265 jy = jy + incy266 kk = kk + j267 40 CONTINUE268 END IF269 ELSE270 *271 * Form A when lower triangle is stored in AP.272 *273 IF ((incx.EQ.1) .AND. (incy.EQ.1)) THEN274 DO 60 j = 1,n275 IF ((x(j).NE.zero) .OR. (y(j).NE.zero)) THEN276 temp1 = alpha*conjg(y(j))277 temp2 = conjg(alpha*x(j))278 ap(kk) = REAL(AP(KK)) +279 + REAL(x(j)*temp1+y(j)*temp2)280 k = kk + 1281 DO 50 i = j + 1,n282 ap(k) = ap(k) + x(i)*temp1 + y(i)*temp2283 k = k + 1284 50 CONTINUE285 ELSE286 ap(kk) = REAL(ap(kk))287 END IF288 kk = kk + n - j + 1289 60 CONTINUE290 ELSE291 DO 80 j = 1,n292 IF ((x(jx).NE.zero) .OR. (y(jy).NE.zero)) THEN293 temp1 = alpha*conjg(y(jy))294 temp2 = conjg(alpha*x(jx))295 ap(kk) = REAL(AP(KK)) +296 + REAL(x(jx)*temp1+y(jy)*temp2)297 ix = jx298 iy = jy299 DO 70 k = kk + 1,kk + n - j300 ix = ix + incx301 iy = iy + incy302 ap(k) = ap(k) + x(ix)*temp1 + y(iy)*temp2303 70 CONTINUE304 ELSE305 ap(kk) = REAL(ap(kk))306 END IF307 jx = jx + incx308 jy = jy + incy309 kk = kk + n - j + 1310 80 CONTINUE311 END IF312 END IF313 *314 RETURN315 *316 * End of CHPR2 .317 * AuthorGenerated automatically by Doxygen for LAPACK from the source code.
Index- NAME
- SYNOPSIS
- Functions/Subroutines
- Function/Subroutine Documentation
- subroutine CHPR2 (character UPLO, integer N, complex ALPHA, complex, dimension(*) X, integer INCX, complex, dimension(*) Y, integer INCY, complex, dimension(*) AP)
- Author
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