# zlargv (l) - Linux Manuals

## zlargv: generates a vector of complex plane rotations with real cosines, determined by elements of the complex vectors x and y

## NAME

ZLARGV - generates 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(

(

where c(i)**2

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)

## 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 overwritten 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 This version has a few statements commented out for thread safety (machine parameters are computed on each entry). 10 feb 03, SJH.