SLARGV generates a vector of real plane rotations, determined by
 elements of the real vectors x and y. For i = 1,2,...,n

    (  c(i)  s(i) ) ( x(i) ) = ( a(i) )
    ( -s(i)  c(i) ) ( y(i) ) = (   0  )

          N is INTEGER
          The number of plane rotations to be generated.

          X is REAL array,
                         dimension (1+(N-1)*INCX)
          On entry, the vector x.
          On exit, x(i) is overwritten by a(i), for i = 1,...,n.

          INCX is INTEGER
          The increment between elements of X. INCX > 0.

          Y is REAL array,
                         dimension (1+(N-1)*INCY)
          On entry, the vector y.
          On exit, the sines of the plane rotations.

          INCY is INTEGER
          The increment between elements of Y. INCY > 0.

          C is REAL array, dimension (1+(N-1)*INCC)
          The cosines of the plane rotations.

          INCC is INTEGER
          The increment between elements of C. INCC > 0.