man clargv (Fonctions bibliothèques) - generate a vector of complex plane rotations with real cosines, determined by elements of the complex vectors x and y

NAME

CLARGV - generate a vector of complex plane rotations with real cosines, determined by elements of the complex vectors x and y

SYNOPSIS

SUBROUTINE CLARGV(
N, X, INCX, Y, INCY, C, INCC )
INTEGER INCC, INCX, INCY, N
REAL C( * )
COMPLEX X( * ), Y( * )

PURPOSE

CLARGV 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 CLARTG, but differ from the BLAS1 routine CROTG):

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 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 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) REAL 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