Annotation of rpl/lapack/blas/zgemv.f, revision 1.1
1.1 ! bertrand 1: SUBROUTINE ZGEMV(TRANS,M,N,ALPHA,A,LDA,X,INCX,BETA,Y,INCY)
! 2: * .. Scalar Arguments ..
! 3: DOUBLE COMPLEX ALPHA,BETA
! 4: INTEGER INCX,INCY,LDA,M,N
! 5: CHARACTER TRANS
! 6: * ..
! 7: * .. Array Arguments ..
! 8: DOUBLE COMPLEX A(LDA,*),X(*),Y(*)
! 9: * ..
! 10: *
! 11: * Purpose
! 12: * =======
! 13: *
! 14: * ZGEMV performs one of the matrix-vector operations
! 15: *
! 16: * y := alpha*A*x + beta*y, or y := alpha*A'*x + beta*y, or
! 17: *
! 18: * y := alpha*conjg( A' )*x + beta*y,
! 19: *
! 20: * where alpha and beta are scalars, x and y are vectors and A is an
! 21: * m by n matrix.
! 22: *
! 23: * Arguments
! 24: * ==========
! 25: *
! 26: * TRANS - CHARACTER*1.
! 27: * On entry, TRANS specifies the operation to be performed as
! 28: * follows:
! 29: *
! 30: * TRANS = 'N' or 'n' y := alpha*A*x + beta*y.
! 31: *
! 32: * TRANS = 'T' or 't' y := alpha*A'*x + beta*y.
! 33: *
! 34: * TRANS = 'C' or 'c' y := alpha*conjg( A' )*x + beta*y.
! 35: *
! 36: * Unchanged on exit.
! 37: *
! 38: * M - INTEGER.
! 39: * On entry, M specifies the number of rows of the matrix A.
! 40: * M must be at least zero.
! 41: * Unchanged on exit.
! 42: *
! 43: * N - INTEGER.
! 44: * On entry, N specifies the number of columns of the matrix A.
! 45: * N must be at least zero.
! 46: * Unchanged on exit.
! 47: *
! 48: * ALPHA - COMPLEX*16 .
! 49: * On entry, ALPHA specifies the scalar alpha.
! 50: * Unchanged on exit.
! 51: *
! 52: * A - COMPLEX*16 array of DIMENSION ( LDA, n ).
! 53: * Before entry, the leading m by n part of the array A must
! 54: * contain the matrix of coefficients.
! 55: * Unchanged on exit.
! 56: *
! 57: * LDA - INTEGER.
! 58: * On entry, LDA specifies the first dimension of A as declared
! 59: * in the calling (sub) program. LDA must be at least
! 60: * max( 1, m ).
! 61: * Unchanged on exit.
! 62: *
! 63: * X - COMPLEX*16 array of DIMENSION at least
! 64: * ( 1 + ( n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n'
! 65: * and at least
! 66: * ( 1 + ( m - 1 )*abs( INCX ) ) otherwise.
! 67: * Before entry, the incremented array X must contain the
! 68: * vector x.
! 69: * Unchanged on exit.
! 70: *
! 71: * INCX - INTEGER.
! 72: * On entry, INCX specifies the increment for the elements of
! 73: * X. INCX must not be zero.
! 74: * Unchanged on exit.
! 75: *
! 76: * BETA - COMPLEX*16 .
! 77: * On entry, BETA specifies the scalar beta. When BETA is
! 78: * supplied as zero then Y need not be set on input.
! 79: * Unchanged on exit.
! 80: *
! 81: * Y - COMPLEX*16 array of DIMENSION at least
! 82: * ( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N' or 'n'
! 83: * and at least
! 84: * ( 1 + ( n - 1 )*abs( INCY ) ) otherwise.
! 85: * Before entry with BETA non-zero, the incremented array Y
! 86: * must contain the vector y. On exit, Y is overwritten by the
! 87: * updated vector y.
! 88: *
! 89: * INCY - INTEGER.
! 90: * On entry, INCY specifies the increment for the elements of
! 91: * Y. INCY must not be zero.
! 92: * Unchanged on exit.
! 93: *
! 94: * Further Details
! 95: * ===============
! 96: *
! 97: * Level 2 Blas routine.
! 98: *
! 99: * -- Written on 22-October-1986.
! 100: * Jack Dongarra, Argonne National Lab.
! 101: * Jeremy Du Croz, Nag Central Office.
! 102: * Sven Hammarling, Nag Central Office.
! 103: * Richard Hanson, Sandia National Labs.
! 104: *
! 105: * =====================================================================
! 106: *
! 107: * .. Parameters ..
! 108: DOUBLE COMPLEX ONE
! 109: PARAMETER (ONE= (1.0D+0,0.0D+0))
! 110: DOUBLE COMPLEX ZERO
! 111: PARAMETER (ZERO= (0.0D+0,0.0D+0))
! 112: * ..
! 113: * .. Local Scalars ..
! 114: DOUBLE COMPLEX TEMP
! 115: INTEGER I,INFO,IX,IY,J,JX,JY,KX,KY,LENX,LENY
! 116: LOGICAL NOCONJ
! 117: * ..
! 118: * .. External Functions ..
! 119: LOGICAL LSAME
! 120: EXTERNAL LSAME
! 121: * ..
! 122: * .. External Subroutines ..
! 123: EXTERNAL XERBLA
! 124: * ..
! 125: * .. Intrinsic Functions ..
! 126: INTRINSIC DCONJG,MAX
! 127: * ..
! 128: *
! 129: * Test the input parameters.
! 130: *
! 131: INFO = 0
! 132: IF (.NOT.LSAME(TRANS,'N') .AND. .NOT.LSAME(TRANS,'T') .AND.
! 133: + .NOT.LSAME(TRANS,'C')) THEN
! 134: INFO = 1
! 135: ELSE IF (M.LT.0) THEN
! 136: INFO = 2
! 137: ELSE IF (N.LT.0) THEN
! 138: INFO = 3
! 139: ELSE IF (LDA.LT.MAX(1,M)) THEN
! 140: INFO = 6
! 141: ELSE IF (INCX.EQ.0) THEN
! 142: INFO = 8
! 143: ELSE IF (INCY.EQ.0) THEN
! 144: INFO = 11
! 145: END IF
! 146: IF (INFO.NE.0) THEN
! 147: CALL XERBLA('ZGEMV ',INFO)
! 148: RETURN
! 149: END IF
! 150: *
! 151: * Quick return if possible.
! 152: *
! 153: IF ((M.EQ.0) .OR. (N.EQ.0) .OR.
! 154: + ((ALPHA.EQ.ZERO).AND. (BETA.EQ.ONE))) RETURN
! 155: *
! 156: NOCONJ = LSAME(TRANS,'T')
! 157: *
! 158: * Set LENX and LENY, the lengths of the vectors x and y, and set
! 159: * up the start points in X and Y.
! 160: *
! 161: IF (LSAME(TRANS,'N')) THEN
! 162: LENX = N
! 163: LENY = M
! 164: ELSE
! 165: LENX = M
! 166: LENY = N
! 167: END IF
! 168: IF (INCX.GT.0) THEN
! 169: KX = 1
! 170: ELSE
! 171: KX = 1 - (LENX-1)*INCX
! 172: END IF
! 173: IF (INCY.GT.0) THEN
! 174: KY = 1
! 175: ELSE
! 176: KY = 1 - (LENY-1)*INCY
! 177: END IF
! 178: *
! 179: * Start the operations. In this version the elements of A are
! 180: * accessed sequentially with one pass through A.
! 181: *
! 182: * First form y := beta*y.
! 183: *
! 184: IF (BETA.NE.ONE) THEN
! 185: IF (INCY.EQ.1) THEN
! 186: IF (BETA.EQ.ZERO) THEN
! 187: DO 10 I = 1,LENY
! 188: Y(I) = ZERO
! 189: 10 CONTINUE
! 190: ELSE
! 191: DO 20 I = 1,LENY
! 192: Y(I) = BETA*Y(I)
! 193: 20 CONTINUE
! 194: END IF
! 195: ELSE
! 196: IY = KY
! 197: IF (BETA.EQ.ZERO) THEN
! 198: DO 30 I = 1,LENY
! 199: Y(IY) = ZERO
! 200: IY = IY + INCY
! 201: 30 CONTINUE
! 202: ELSE
! 203: DO 40 I = 1,LENY
! 204: Y(IY) = BETA*Y(IY)
! 205: IY = IY + INCY
! 206: 40 CONTINUE
! 207: END IF
! 208: END IF
! 209: END IF
! 210: IF (ALPHA.EQ.ZERO) RETURN
! 211: IF (LSAME(TRANS,'N')) THEN
! 212: *
! 213: * Form y := alpha*A*x + y.
! 214: *
! 215: JX = KX
! 216: IF (INCY.EQ.1) THEN
! 217: DO 60 J = 1,N
! 218: IF (X(JX).NE.ZERO) THEN
! 219: TEMP = ALPHA*X(JX)
! 220: DO 50 I = 1,M
! 221: Y(I) = Y(I) + TEMP*A(I,J)
! 222: 50 CONTINUE
! 223: END IF
! 224: JX = JX + INCX
! 225: 60 CONTINUE
! 226: ELSE
! 227: DO 80 J = 1,N
! 228: IF (X(JX).NE.ZERO) THEN
! 229: TEMP = ALPHA*X(JX)
! 230: IY = KY
! 231: DO 70 I = 1,M
! 232: Y(IY) = Y(IY) + TEMP*A(I,J)
! 233: IY = IY + INCY
! 234: 70 CONTINUE
! 235: END IF
! 236: JX = JX + INCX
! 237: 80 CONTINUE
! 238: END IF
! 239: ELSE
! 240: *
! 241: * Form y := alpha*A'*x + y or y := alpha*conjg( A' )*x + y.
! 242: *
! 243: JY = KY
! 244: IF (INCX.EQ.1) THEN
! 245: DO 110 J = 1,N
! 246: TEMP = ZERO
! 247: IF (NOCONJ) THEN
! 248: DO 90 I = 1,M
! 249: TEMP = TEMP + A(I,J)*X(I)
! 250: 90 CONTINUE
! 251: ELSE
! 252: DO 100 I = 1,M
! 253: TEMP = TEMP + DCONJG(A(I,J))*X(I)
! 254: 100 CONTINUE
! 255: END IF
! 256: Y(JY) = Y(JY) + ALPHA*TEMP
! 257: JY = JY + INCY
! 258: 110 CONTINUE
! 259: ELSE
! 260: DO 140 J = 1,N
! 261: TEMP = ZERO
! 262: IX = KX
! 263: IF (NOCONJ) THEN
! 264: DO 120 I = 1,M
! 265: TEMP = TEMP + A(I,J)*X(IX)
! 266: IX = IX + INCX
! 267: 120 CONTINUE
! 268: ELSE
! 269: DO 130 I = 1,M
! 270: TEMP = TEMP + DCONJG(A(I,J))*X(IX)
! 271: IX = IX + INCX
! 272: 130 CONTINUE
! 273: END IF
! 274: Y(JY) = Y(JY) + ALPHA*TEMP
! 275: JY = JY + INCY
! 276: 140 CONTINUE
! 277: END IF
! 278: END IF
! 279: *
! 280: RETURN
! 281: *
! 282: * End of ZGEMV .
! 283: *
! 284: END
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