zlargv(3)

NAME

ZLARGV - generate a vector of complex plane rotations with

real cosines, determined by elements of the complex vectors x and

y

SYNOPSIS

SUBROUTINE ZLARGV( N, X, INCX, Y, INCY, C, INCC )
    INTEGER        INCC, INCX, INCY, N
    DOUBLE         PRECISION C( * )
    COMPLEX*16     X( * ), Y( * )

PURPOSE

ZLARGV generates a vector of complex plane rotations with

real cosines, determined by elements of the complex vectors x and

y. For i = 1,2,...,n

( c(i) s(i) ) ( x(i) ) = ( r(i) )
( -conjg(s(i)) c(i) ) ( y(i) ) = ( 0 )

where c(i)**2 + ABS(s(i))**2 = 1

The following conventions are used (these are the same as

in ZLARTG, but differ from the BLAS1 routine ZROTG):

If y(i)=0, then c(i)=1 and s(i)=0.
If x(i)=0, then c(i)=0 and s(i) is chosen so that r(i)

is real.

ARGUMENTS

N (input) INTEGER

The number of plane rotations to be generated.

X (input/output) COMPLEX*16 array, dimension

(1+(N-1)*INCX)

On entry, the vector x. On exit, x(i) is over

written by r(i), for i = 1,...,n.

INCX (input) INTEGER

The increment between elements of X. INCX > 0.

Y (input/output) COMPLEX*16 array, dimension

(1+(N-1)*INCY)

On entry, the vector y. On exit, the sines of the

plane rotations.

INCY (input) INTEGER

The increment between elements of Y. INCY > 0.

C (output) DOUBLE PRECISION array, dimension

(1+(N-1)*INCC)

The cosines of the plane rotations.

INCC (input) INTEGER

The increment between elements of C. INCC > 0.

FURTHER DETAILS

6-6-96 - Modified with a new algorithm by W. Kahan and J.

Demmel

LAPACK version 3.0 15 June 2000

ZLARGV(3)