|
1
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 |
SUBROUTINE CHERK(UPLO,TRANS,N,K,ALPHA,A,LDA,BETA,C,LDC)
* .. Scalar Arguments .. REAL ALPHA,BETA INTEGER K,LDA,LDC,N CHARACTER TRANS,UPLO * .. * .. Array Arguments .. COMPLEX A(LDA,*),C(LDC,*) * .. * * 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. * * Arguments * ========== * * UPLO - 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. * * Unchanged on exit. * * TRANS - 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. * * Unchanged on exit. * * N - INTEGER. * On entry, N specifies the order of the matrix C. N must be * at least zero. * Unchanged on exit. * * K - 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. * Unchanged on exit. * * ALPHA - REAL . * On entry, ALPHA specifies the scalar alpha. * Unchanged on exit. * * A - 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. * Unchanged on exit. * * LDA - 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 ). * Unchanged on exit. * * BETA - REAL . * On entry, BETA specifies the scalar beta. * Unchanged on exit. * * C - 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 - 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 ). * Unchanged on exit. * * 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. * * ===================================================================== * * .. External Functions .. LOGICAL LSAME EXTERNAL LSAME * .. * .. External Subroutines .. EXTERNAL XERBLA * .. * .. Intrinsic Functions .. INTRINSIC CMPLX,CONJG,MAX,REAL * .. * .. Local Scalars .. COMPLEX TEMP REAL RTEMP INTEGER I,INFO,J,L,NROWA LOGICAL UPPER * .. * .. Parameters .. REAL ONE,ZERO PARAMETER (ONE=1.0E+0,ZERO=0.0E+0) * .. * * Test the input parameters. * IF (LSAME(TRANS,'N')) THEN NROWA = N ELSE NROWA = K END IF UPPER = LSAME(UPLO,'U') * INFO = 0 IF ((.NOT.UPPER) .AND. (.NOT.LSAME(UPLO,'L'))) THEN INFO = 1 ELSE IF ((.NOT.LSAME(TRANS,'N')) .AND. + (.NOT.LSAME(TRANS,'C'))) THEN INFO = 2 ELSE IF (N.LT.0) THEN INFO = 3 ELSE IF (K.LT.0) THEN INFO = 4 ELSE IF (LDA.LT.MAX(1,NROWA)) THEN INFO = 7 ELSE IF (LDC.LT.MAX(1,N)) THEN INFO = 10 END IF IF (INFO.NE.0) THEN CALL XERBLA('CHERK ',INFO) RETURN END IF * * Quick return if possible. * IF ((N.EQ.0) .OR. (((ALPHA.EQ.ZERO).OR. + (K.EQ.0)).AND. (BETA.EQ.ONE))) RETURN * * And when alpha.eq.zero. * IF (ALPHA.EQ.ZERO) THEN IF (UPPER) THEN IF (BETA.EQ.ZERO) THEN DO 20 J = 1,N DO 10 I = 1,J C(I,J) = ZERO 10 CONTINUE 20 CONTINUE ELSE DO 40 J = 1,N DO 30 I = 1,J - 1 C(I,J) = BETA*C(I,J) 30 CONTINUE C(J,J) = BETA*REAL(C(J,J)) 40 CONTINUE END IF ELSE IF (BETA.EQ.ZERO) THEN DO 60 J = 1,N DO 50 I = J,N C(I,J) = ZERO 50 CONTINUE 60 CONTINUE ELSE DO 80 J = 1,N C(J,J) = BETA*REAL(C(J,J)) DO 70 I = J + 1,N C(I,J) = BETA*C(I,J) 70 CONTINUE 80 CONTINUE END IF END IF RETURN END IF * * Start the operations. * IF (LSAME(TRANS,'N')) THEN * * Form C := alpha*A*A**H + beta*C. * IF (UPPER) THEN DO 130 J = 1,N IF (BETA.EQ.ZERO) THEN DO 90 I = 1,J C(I,J) = ZERO 90 CONTINUE ELSE IF (BETA.NE.ONE) THEN DO 100 I = 1,J - 1 C(I,J) = BETA*C(I,J) 100 CONTINUE C(J,J) = BETA*REAL(C(J,J)) ELSE C(J,J) = REAL(C(J,J)) END IF DO 120 L = 1,K IF (A(J,L).NE.CMPLX(ZERO)) THEN TEMP = ALPHA*CONJG(A(J,L)) DO 110 I = 1,J - 1 C(I,J) = C(I,J) + TEMP*A(I,L) 110 CONTINUE C(J,J) = REAL(C(J,J)) + REAL(TEMP*A(I,L)) END IF 120 CONTINUE 130 CONTINUE ELSE DO 180 J = 1,N IF (BETA.EQ.ZERO) THEN DO 140 I = J,N C(I,J) = ZERO 140 CONTINUE ELSE IF (BETA.NE.ONE) THEN C(J,J) = BETA*REAL(C(J,J)) DO 150 I = J + 1,N C(I,J) = BETA*C(I,J) 150 CONTINUE ELSE C(J,J) = REAL(C(J,J)) END IF DO 170 L = 1,K IF (A(J,L).NE.CMPLX(ZERO)) THEN TEMP = ALPHA*CONJG(A(J,L)) C(J,J) = REAL(C(J,J)) + REAL(TEMP*A(J,L)) DO 160 I = J + 1,N C(I,J) = C(I,J) + TEMP*A(I,L) 160 CONTINUE END IF 170 CONTINUE 180 CONTINUE END IF ELSE * * Form C := alpha*A**H*A + beta*C. * IF (UPPER) THEN DO 220 J = 1,N DO 200 I = 1,J - 1 TEMP = ZERO DO 190 L = 1,K TEMP = TEMP + CONJG(A(L,I))*A(L,J) 190 CONTINUE IF (BETA.EQ.ZERO) THEN C(I,J) = ALPHA*TEMP ELSE C(I,J) = ALPHA*TEMP + BETA*C(I,J) END IF 200 CONTINUE RTEMP = ZERO DO 210 L = 1,K RTEMP = RTEMP + CONJG(A(L,J))*A(L,J) 210 CONTINUE IF (BETA.EQ.ZERO) THEN C(J,J) = ALPHA*RTEMP ELSE C(J,J) = ALPHA*RTEMP + BETA*REAL(C(J,J)) END IF 220 CONTINUE ELSE DO 260 J = 1,N RTEMP = ZERO DO 230 L = 1,K RTEMP = RTEMP + CONJG(A(L,J))*A(L,J) 230 CONTINUE IF (BETA.EQ.ZERO) THEN C(J,J) = ALPHA*RTEMP ELSE C(J,J) = ALPHA*RTEMP + BETA*REAL(C(J,J)) END IF DO 250 I = J + 1,N TEMP = ZERO DO 240 L = 1,K TEMP = TEMP + CONJG(A(L,I))*A(L,J) 240 CONTINUE IF (BETA.EQ.ZERO) THEN C(I,J) = ALPHA*TEMP ELSE C(I,J) = ALPHA*TEMP + BETA*C(I,J) END IF 250 CONTINUE 260 CONTINUE END IF END IF * RETURN * * End of CHERK . * END |