Annotation of rpl/lapack/blas/zsyrk.f, revision 1.1
1.1 ! bertrand 1: SUBROUTINE ZSYRK(UPLO,TRANS,N,K,ALPHA,A,LDA,BETA,C,LDC)
! 2: * .. Scalar Arguments ..
! 3: DOUBLE COMPLEX ALPHA,BETA
! 4: INTEGER K,LDA,LDC,N
! 5: CHARACTER TRANS,UPLO
! 6: * ..
! 7: * .. Array Arguments ..
! 8: DOUBLE COMPLEX A(LDA,*),C(LDC,*)
! 9: * ..
! 10: *
! 11: * Purpose
! 12: * =======
! 13: *
! 14: * ZSYRK performs one of the symmetric rank k operations
! 15: *
! 16: * C := alpha*A*A' + beta*C,
! 17: *
! 18: * or
! 19: *
! 20: * C := alpha*A'*A + beta*C,
! 21: *
! 22: * where alpha and beta are scalars, C is an n by n symmetric matrix
! 23: * and A is an n by k matrix in the first case and a k by n matrix
! 24: * in the second case.
! 25: *
! 26: * Arguments
! 27: * ==========
! 28: *
! 29: * UPLO - CHARACTER*1.
! 30: * On entry, UPLO specifies whether the upper or lower
! 31: * triangular part of the array C is to be referenced as
! 32: * follows:
! 33: *
! 34: * UPLO = 'U' or 'u' Only the upper triangular part of C
! 35: * is to be referenced.
! 36: *
! 37: * UPLO = 'L' or 'l' Only the lower triangular part of C
! 38: * is to be referenced.
! 39: *
! 40: * Unchanged on exit.
! 41: *
! 42: * TRANS - CHARACTER*1.
! 43: * On entry, TRANS specifies the operation to be performed as
! 44: * follows:
! 45: *
! 46: * TRANS = 'N' or 'n' C := alpha*A*A' + beta*C.
! 47: *
! 48: * TRANS = 'T' or 't' C := alpha*A'*A + beta*C.
! 49: *
! 50: * Unchanged on exit.
! 51: *
! 52: * N - INTEGER.
! 53: * On entry, N specifies the order of the matrix C. N must be
! 54: * at least zero.
! 55: * Unchanged on exit.
! 56: *
! 57: * K - INTEGER.
! 58: * On entry with TRANS = 'N' or 'n', K specifies the number
! 59: * of columns of the matrix A, and on entry with
! 60: * TRANS = 'T' or 't', K specifies the number of rows of the
! 61: * matrix A. K must be at least zero.
! 62: * Unchanged on exit.
! 63: *
! 64: * ALPHA - COMPLEX*16 .
! 65: * On entry, ALPHA specifies the scalar alpha.
! 66: * Unchanged on exit.
! 67: *
! 68: * A - COMPLEX*16 array of DIMENSION ( LDA, ka ), where ka is
! 69: * k when TRANS = 'N' or 'n', and is n otherwise.
! 70: * Before entry with TRANS = 'N' or 'n', the leading n by k
! 71: * part of the array A must contain the matrix A, otherwise
! 72: * the leading k by n part of the array A must contain the
! 73: * matrix A.
! 74: * Unchanged on exit.
! 75: *
! 76: * LDA - INTEGER.
! 77: * On entry, LDA specifies the first dimension of A as declared
! 78: * in the calling (sub) program. When TRANS = 'N' or 'n'
! 79: * then LDA must be at least max( 1, n ), otherwise LDA must
! 80: * be at least max( 1, k ).
! 81: * Unchanged on exit.
! 82: *
! 83: * BETA - COMPLEX*16 .
! 84: * On entry, BETA specifies the scalar beta.
! 85: * Unchanged on exit.
! 86: *
! 87: * C - COMPLEX*16 array of DIMENSION ( LDC, n ).
! 88: * Before entry with UPLO = 'U' or 'u', the leading n by n
! 89: * upper triangular part of the array C must contain the upper
! 90: * triangular part of the symmetric matrix and the strictly
! 91: * lower triangular part of C is not referenced. On exit, the
! 92: * upper triangular part of the array C is overwritten by the
! 93: * upper triangular part of the updated matrix.
! 94: * Before entry with UPLO = 'L' or 'l', the leading n by n
! 95: * lower triangular part of the array C must contain the lower
! 96: * triangular part of the symmetric matrix and the strictly
! 97: * upper triangular part of C is not referenced. On exit, the
! 98: * lower triangular part of the array C is overwritten by the
! 99: * lower triangular part of the updated matrix.
! 100: *
! 101: * LDC - INTEGER.
! 102: * On entry, LDC specifies the first dimension of C as declared
! 103: * in the calling (sub) program. LDC must be at least
! 104: * max( 1, n ).
! 105: * Unchanged on exit.
! 106: *
! 107: * Further Details
! 108: * ===============
! 109: *
! 110: * Level 3 Blas routine.
! 111: *
! 112: * -- Written on 8-February-1989.
! 113: * Jack Dongarra, Argonne National Laboratory.
! 114: * Iain Duff, AERE Harwell.
! 115: * Jeremy Du Croz, Numerical Algorithms Group Ltd.
! 116: * Sven Hammarling, Numerical Algorithms Group Ltd.
! 117: *
! 118: * =====================================================================
! 119: *
! 120: * .. External Functions ..
! 121: LOGICAL LSAME
! 122: EXTERNAL LSAME
! 123: * ..
! 124: * .. External Subroutines ..
! 125: EXTERNAL XERBLA
! 126: * ..
! 127: * .. Intrinsic Functions ..
! 128: INTRINSIC MAX
! 129: * ..
! 130: * .. Local Scalars ..
! 131: DOUBLE COMPLEX TEMP
! 132: INTEGER I,INFO,J,L,NROWA
! 133: LOGICAL UPPER
! 134: * ..
! 135: * .. Parameters ..
! 136: DOUBLE COMPLEX ONE
! 137: PARAMETER (ONE= (1.0D+0,0.0D+0))
! 138: DOUBLE COMPLEX ZERO
! 139: PARAMETER (ZERO= (0.0D+0,0.0D+0))
! 140: * ..
! 141: *
! 142: * Test the input parameters.
! 143: *
! 144: IF (LSAME(TRANS,'N')) THEN
! 145: NROWA = N
! 146: ELSE
! 147: NROWA = K
! 148: END IF
! 149: UPPER = LSAME(UPLO,'U')
! 150: *
! 151: INFO = 0
! 152: IF ((.NOT.UPPER) .AND. (.NOT.LSAME(UPLO,'L'))) THEN
! 153: INFO = 1
! 154: ELSE IF ((.NOT.LSAME(TRANS,'N')) .AND.
! 155: + (.NOT.LSAME(TRANS,'T'))) THEN
! 156: INFO = 2
! 157: ELSE IF (N.LT.0) THEN
! 158: INFO = 3
! 159: ELSE IF (K.LT.0) THEN
! 160: INFO = 4
! 161: ELSE IF (LDA.LT.MAX(1,NROWA)) THEN
! 162: INFO = 7
! 163: ELSE IF (LDC.LT.MAX(1,N)) THEN
! 164: INFO = 10
! 165: END IF
! 166: IF (INFO.NE.0) THEN
! 167: CALL XERBLA('ZSYRK ',INFO)
! 168: RETURN
! 169: END IF
! 170: *
! 171: * Quick return if possible.
! 172: *
! 173: IF ((N.EQ.0) .OR. (((ALPHA.EQ.ZERO).OR.
! 174: + (K.EQ.0)).AND. (BETA.EQ.ONE))) RETURN
! 175: *
! 176: * And when alpha.eq.zero.
! 177: *
! 178: IF (ALPHA.EQ.ZERO) THEN
! 179: IF (UPPER) THEN
! 180: IF (BETA.EQ.ZERO) THEN
! 181: DO 20 J = 1,N
! 182: DO 10 I = 1,J
! 183: C(I,J) = ZERO
! 184: 10 CONTINUE
! 185: 20 CONTINUE
! 186: ELSE
! 187: DO 40 J = 1,N
! 188: DO 30 I = 1,J
! 189: C(I,J) = BETA*C(I,J)
! 190: 30 CONTINUE
! 191: 40 CONTINUE
! 192: END IF
! 193: ELSE
! 194: IF (BETA.EQ.ZERO) THEN
! 195: DO 60 J = 1,N
! 196: DO 50 I = J,N
! 197: C(I,J) = ZERO
! 198: 50 CONTINUE
! 199: 60 CONTINUE
! 200: ELSE
! 201: DO 80 J = 1,N
! 202: DO 70 I = J,N
! 203: C(I,J) = BETA*C(I,J)
! 204: 70 CONTINUE
! 205: 80 CONTINUE
! 206: END IF
! 207: END IF
! 208: RETURN
! 209: END IF
! 210: *
! 211: * Start the operations.
! 212: *
! 213: IF (LSAME(TRANS,'N')) THEN
! 214: *
! 215: * Form C := alpha*A*A' + beta*C.
! 216: *
! 217: IF (UPPER) THEN
! 218: DO 130 J = 1,N
! 219: IF (BETA.EQ.ZERO) THEN
! 220: DO 90 I = 1,J
! 221: C(I,J) = ZERO
! 222: 90 CONTINUE
! 223: ELSE IF (BETA.NE.ONE) THEN
! 224: DO 100 I = 1,J
! 225: C(I,J) = BETA*C(I,J)
! 226: 100 CONTINUE
! 227: END IF
! 228: DO 120 L = 1,K
! 229: IF (A(J,L).NE.ZERO) THEN
! 230: TEMP = ALPHA*A(J,L)
! 231: DO 110 I = 1,J
! 232: C(I,J) = C(I,J) + TEMP*A(I,L)
! 233: 110 CONTINUE
! 234: END IF
! 235: 120 CONTINUE
! 236: 130 CONTINUE
! 237: ELSE
! 238: DO 180 J = 1,N
! 239: IF (BETA.EQ.ZERO) THEN
! 240: DO 140 I = J,N
! 241: C(I,J) = ZERO
! 242: 140 CONTINUE
! 243: ELSE IF (BETA.NE.ONE) THEN
! 244: DO 150 I = J,N
! 245: C(I,J) = BETA*C(I,J)
! 246: 150 CONTINUE
! 247: END IF
! 248: DO 170 L = 1,K
! 249: IF (A(J,L).NE.ZERO) THEN
! 250: TEMP = ALPHA*A(J,L)
! 251: DO 160 I = J,N
! 252: C(I,J) = C(I,J) + TEMP*A(I,L)
! 253: 160 CONTINUE
! 254: END IF
! 255: 170 CONTINUE
! 256: 180 CONTINUE
! 257: END IF
! 258: ELSE
! 259: *
! 260: * Form C := alpha*A'*A + beta*C.
! 261: *
! 262: IF (UPPER) THEN
! 263: DO 210 J = 1,N
! 264: DO 200 I = 1,J
! 265: TEMP = ZERO
! 266: DO 190 L = 1,K
! 267: TEMP = TEMP + A(L,I)*A(L,J)
! 268: 190 CONTINUE
! 269: IF (BETA.EQ.ZERO) THEN
! 270: C(I,J) = ALPHA*TEMP
! 271: ELSE
! 272: C(I,J) = ALPHA*TEMP + BETA*C(I,J)
! 273: END IF
! 274: 200 CONTINUE
! 275: 210 CONTINUE
! 276: ELSE
! 277: DO 240 J = 1,N
! 278: DO 230 I = J,N
! 279: TEMP = ZERO
! 280: DO 220 L = 1,K
! 281: TEMP = TEMP + A(L,I)*A(L,J)
! 282: 220 CONTINUE
! 283: IF (BETA.EQ.ZERO) THEN
! 284: C(I,J) = ALPHA*TEMP
! 285: ELSE
! 286: C(I,J) = ALPHA*TEMP + BETA*C(I,J)
! 287: END IF
! 288: 230 CONTINUE
! 289: 240 CONTINUE
! 290: END IF
! 291: END IF
! 292: *
! 293: RETURN
! 294: *
! 295: * End of ZSYRK .
! 296: *
! 297: END
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