Annotation of rpl/lapack/blas/zhpr.f, revision 1.1
1.1 ! bertrand 1: SUBROUTINE ZHPR(UPLO,N,ALPHA,X,INCX,AP)
! 2: * .. Scalar Arguments ..
! 3: DOUBLE PRECISION ALPHA
! 4: INTEGER INCX,N
! 5: CHARACTER UPLO
! 6: * ..
! 7: * .. Array Arguments ..
! 8: DOUBLE COMPLEX AP(*),X(*)
! 9: * ..
! 10: *
! 11: * Purpose
! 12: * =======
! 13: *
! 14: * ZHPR performs the hermitian rank 1 operation
! 15: *
! 16: * A := alpha*x*conjg( x' ) + A,
! 17: *
! 18: * where alpha is a real scalar, x is an n element vector and A is an
! 19: * n by n hermitian matrix, supplied in packed form.
! 20: *
! 21: * Arguments
! 22: * ==========
! 23: *
! 24: * UPLO - CHARACTER*1.
! 25: * On entry, UPLO specifies whether the upper or lower
! 26: * triangular part of the matrix A is supplied in the packed
! 27: * array AP as follows:
! 28: *
! 29: * UPLO = 'U' or 'u' The upper triangular part of A is
! 30: * supplied in AP.
! 31: *
! 32: * UPLO = 'L' or 'l' The lower triangular part of A is
! 33: * supplied in AP.
! 34: *
! 35: * Unchanged on exit.
! 36: *
! 37: * N - INTEGER.
! 38: * On entry, N specifies the order of the matrix A.
! 39: * N must be at least zero.
! 40: * Unchanged on exit.
! 41: *
! 42: * ALPHA - DOUBLE PRECISION.
! 43: * On entry, ALPHA specifies the scalar alpha.
! 44: * Unchanged on exit.
! 45: *
! 46: * X - COMPLEX*16 array of dimension at least
! 47: * ( 1 + ( n - 1 )*abs( INCX ) ).
! 48: * Before entry, the incremented array X must contain the n
! 49: * element vector x.
! 50: * Unchanged on exit.
! 51: *
! 52: * INCX - INTEGER.
! 53: * On entry, INCX specifies the increment for the elements of
! 54: * X. INCX must not be zero.
! 55: * Unchanged on exit.
! 56: *
! 57: * AP - COMPLEX*16 array of DIMENSION at least
! 58: * ( ( n*( n + 1 ) )/2 ).
! 59: * Before entry with UPLO = 'U' or 'u', the array AP must
! 60: * contain the upper triangular part of the hermitian matrix
! 61: * packed sequentially, column by column, so that AP( 1 )
! 62: * contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 )
! 63: * and a( 2, 2 ) respectively, and so on. On exit, the array
! 64: * AP is overwritten by the upper triangular part of the
! 65: * updated matrix.
! 66: * Before entry with UPLO = 'L' or 'l', the array AP must
! 67: * contain the lower triangular part of the hermitian matrix
! 68: * packed sequentially, column by column, so that AP( 1 )
! 69: * contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 )
! 70: * and a( 3, 1 ) respectively, and so on. On exit, the array
! 71: * AP is overwritten by the lower triangular part of the
! 72: * updated matrix.
! 73: * Note that the imaginary parts of the diagonal elements need
! 74: * not be set, they are assumed to be zero, and on exit they
! 75: * are set to zero.
! 76: *
! 77: * Further Details
! 78: * ===============
! 79: *
! 80: * Level 2 Blas routine.
! 81: *
! 82: * -- Written on 22-October-1986.
! 83: * Jack Dongarra, Argonne National Lab.
! 84: * Jeremy Du Croz, Nag Central Office.
! 85: * Sven Hammarling, Nag Central Office.
! 86: * Richard Hanson, Sandia National Labs.
! 87: *
! 88: * =====================================================================
! 89: *
! 90: * .. Parameters ..
! 91: DOUBLE COMPLEX ZERO
! 92: PARAMETER (ZERO= (0.0D+0,0.0D+0))
! 93: * ..
! 94: * .. Local Scalars ..
! 95: DOUBLE COMPLEX TEMP
! 96: INTEGER I,INFO,IX,J,JX,K,KK,KX
! 97: * ..
! 98: * .. External Functions ..
! 99: LOGICAL LSAME
! 100: EXTERNAL LSAME
! 101: * ..
! 102: * .. External Subroutines ..
! 103: EXTERNAL XERBLA
! 104: * ..
! 105: * .. Intrinsic Functions ..
! 106: INTRINSIC DBLE,DCONJG
! 107: * ..
! 108: *
! 109: * Test the input parameters.
! 110: *
! 111: INFO = 0
! 112: IF (.NOT.LSAME(UPLO,'U') .AND. .NOT.LSAME(UPLO,'L')) THEN
! 113: INFO = 1
! 114: ELSE IF (N.LT.0) THEN
! 115: INFO = 2
! 116: ELSE IF (INCX.EQ.0) THEN
! 117: INFO = 5
! 118: END IF
! 119: IF (INFO.NE.0) THEN
! 120: CALL XERBLA('ZHPR ',INFO)
! 121: RETURN
! 122: END IF
! 123: *
! 124: * Quick return if possible.
! 125: *
! 126: IF ((N.EQ.0) .OR. (ALPHA.EQ.DBLE(ZERO))) RETURN
! 127: *
! 128: * Set the start point in X if the increment is not unity.
! 129: *
! 130: IF (INCX.LE.0) THEN
! 131: KX = 1 - (N-1)*INCX
! 132: ELSE IF (INCX.NE.1) THEN
! 133: KX = 1
! 134: END IF
! 135: *
! 136: * Start the operations. In this version the elements of the array AP
! 137: * are accessed sequentially with one pass through AP.
! 138: *
! 139: KK = 1
! 140: IF (LSAME(UPLO,'U')) THEN
! 141: *
! 142: * Form A when upper triangle is stored in AP.
! 143: *
! 144: IF (INCX.EQ.1) THEN
! 145: DO 20 J = 1,N
! 146: IF (X(J).NE.ZERO) THEN
! 147: TEMP = ALPHA*DCONJG(X(J))
! 148: K = KK
! 149: DO 10 I = 1,J - 1
! 150: AP(K) = AP(K) + X(I)*TEMP
! 151: K = K + 1
! 152: 10 CONTINUE
! 153: AP(KK+J-1) = DBLE(AP(KK+J-1)) + DBLE(X(J)*TEMP)
! 154: ELSE
! 155: AP(KK+J-1) = DBLE(AP(KK+J-1))
! 156: END IF
! 157: KK = KK + J
! 158: 20 CONTINUE
! 159: ELSE
! 160: JX = KX
! 161: DO 40 J = 1,N
! 162: IF (X(JX).NE.ZERO) THEN
! 163: TEMP = ALPHA*DCONJG(X(JX))
! 164: IX = KX
! 165: DO 30 K = KK,KK + J - 2
! 166: AP(K) = AP(K) + X(IX)*TEMP
! 167: IX = IX + INCX
! 168: 30 CONTINUE
! 169: AP(KK+J-1) = DBLE(AP(KK+J-1)) + DBLE(X(JX)*TEMP)
! 170: ELSE
! 171: AP(KK+J-1) = DBLE(AP(KK+J-1))
! 172: END IF
! 173: JX = JX + INCX
! 174: KK = KK + J
! 175: 40 CONTINUE
! 176: END IF
! 177: ELSE
! 178: *
! 179: * Form A when lower triangle is stored in AP.
! 180: *
! 181: IF (INCX.EQ.1) THEN
! 182: DO 60 J = 1,N
! 183: IF (X(J).NE.ZERO) THEN
! 184: TEMP = ALPHA*DCONJG(X(J))
! 185: AP(KK) = DBLE(AP(KK)) + DBLE(TEMP*X(J))
! 186: K = KK + 1
! 187: DO 50 I = J + 1,N
! 188: AP(K) = AP(K) + X(I)*TEMP
! 189: K = K + 1
! 190: 50 CONTINUE
! 191: ELSE
! 192: AP(KK) = DBLE(AP(KK))
! 193: END IF
! 194: KK = KK + N - J + 1
! 195: 60 CONTINUE
! 196: ELSE
! 197: JX = KX
! 198: DO 80 J = 1,N
! 199: IF (X(JX).NE.ZERO) THEN
! 200: TEMP = ALPHA*DCONJG(X(JX))
! 201: AP(KK) = DBLE(AP(KK)) + DBLE(TEMP*X(JX))
! 202: IX = JX
! 203: DO 70 K = KK + 1,KK + N - J
! 204: IX = IX + INCX
! 205: AP(K) = AP(K) + X(IX)*TEMP
! 206: 70 CONTINUE
! 207: ELSE
! 208: AP(KK) = DBLE(AP(KK))
! 209: END IF
! 210: JX = JX + INCX
! 211: KK = KK + N - J + 1
! 212: 80 CONTINUE
! 213: END IF
! 214: END IF
! 215: *
! 216: RETURN
! 217: *
! 218: * End of ZHPR .
! 219: *
! 220: END
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