clargv(3S)

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( * )

IMPLEMENTATION
     These routines are part of the SCSL Scientific Library and can be loaded
     using either the -lscs or the -lscs_mp option.  The -lscs_mp option
     directs the linker to use the multi-processor version of the library.

     When linking to SCSL with -lscs or -lscs_mp, the default integer size is
     4 bytes (32 bits). Another version of SCSL is available in which integers
     are 8 bytes (64 bits).  This version allows the user access to larger
     memory sizes and helps when porting legacy Cray codes.  It can be loaded
     by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
     only one of the two versions; 4-byte integer and 8-byte integer library
     calls cannot be mixed.

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


SEE ALSO
     INTRO_LAPACK(3S), INTRO_SCSL(3S)

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