zlargv(l) - Linux man page

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
( 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 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.