Annotation of rpl/lapack/lapack/zrot.f, revision 1.1
1.1 ! bertrand 1: SUBROUTINE ZROT( N, CX, INCX, CY, INCY, C, S )
! 2: *
! 3: * -- LAPACK auxiliary routine (version 3.2) --
! 4: * -- LAPACK is a software package provided by Univ. of Tennessee, --
! 5: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
! 6: * November 2006
! 7: *
! 8: * .. Scalar Arguments ..
! 9: INTEGER INCX, INCY, N
! 10: DOUBLE PRECISION C
! 11: COMPLEX*16 S
! 12: * ..
! 13: * .. Array Arguments ..
! 14: COMPLEX*16 CX( * ), CY( * )
! 15: * ..
! 16: *
! 17: * Purpose
! 18: * =======
! 19: *
! 20: * ZROT applies a plane rotation, where the cos (C) is real and the
! 21: * sin (S) is complex, and the vectors CX and CY are complex.
! 22: *
! 23: * Arguments
! 24: * =========
! 25: *
! 26: * N (input) INTEGER
! 27: * The number of elements in the vectors CX and CY.
! 28: *
! 29: * CX (input/output) COMPLEX*16 array, dimension (N)
! 30: * On input, the vector X.
! 31: * On output, CX is overwritten with C*X + S*Y.
! 32: *
! 33: * INCX (input) INTEGER
! 34: * The increment between successive values of CY. INCX <> 0.
! 35: *
! 36: * CY (input/output) COMPLEX*16 array, dimension (N)
! 37: * On input, the vector Y.
! 38: * On output, CY is overwritten with -CONJG(S)*X + C*Y.
! 39: *
! 40: * INCY (input) INTEGER
! 41: * The increment between successive values of CY. INCX <> 0.
! 42: *
! 43: * C (input) DOUBLE PRECISION
! 44: * S (input) COMPLEX*16
! 45: * C and S define a rotation
! 46: * [ C S ]
! 47: * [ -conjg(S) C ]
! 48: * where C*C + S*CONJG(S) = 1.0.
! 49: *
! 50: * =====================================================================
! 51: *
! 52: * .. Local Scalars ..
! 53: INTEGER I, IX, IY
! 54: COMPLEX*16 STEMP
! 55: * ..
! 56: * .. Intrinsic Functions ..
! 57: INTRINSIC DCONJG
! 58: * ..
! 59: * .. Executable Statements ..
! 60: *
! 61: IF( N.LE.0 )
! 62: $ RETURN
! 63: IF( INCX.EQ.1 .AND. INCY.EQ.1 )
! 64: $ GO TO 20
! 65: *
! 66: * Code for unequal increments or equal increments not equal to 1
! 67: *
! 68: IX = 1
! 69: IY = 1
! 70: IF( INCX.LT.0 )
! 71: $ IX = ( -N+1 )*INCX + 1
! 72: IF( INCY.LT.0 )
! 73: $ IY = ( -N+1 )*INCY + 1
! 74: DO 10 I = 1, N
! 75: STEMP = C*CX( IX ) + S*CY( IY )
! 76: CY( IY ) = C*CY( IY ) - DCONJG( S )*CX( IX )
! 77: CX( IX ) = STEMP
! 78: IX = IX + INCX
! 79: IY = IY + INCY
! 80: 10 CONTINUE
! 81: RETURN
! 82: *
! 83: * Code for both increments equal to 1
! 84: *
! 85: 20 CONTINUE
! 86: DO 30 I = 1, N
! 87: STEMP = C*CX( I ) + S*CY( I )
! 88: CY( I ) = C*CY( I ) - DCONJG( S )*CX( I )
! 89: CX( I ) = STEMP
! 90: 30 CONTINUE
! 91: RETURN
! 92: END
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