/*
 *  call-seq:
 *     dvector.make_bezier_control_points_for_cubic_in_x(x0, y0, delta_x, a, b, c)
 *  
 *  Replaces contents of _dvector_ by control points for Bezier curve.
 *  The cubic, y(x), is defined from x0 to x0+delta_x.
 *  At location x = x0 + dx, with dx between 0 and delta_x, define y = a*dx^3 + b*dx^2 + c*dx + y0.
 *  This routine replaces the contents of _dest_ by [x1, y1, x2, y2, x3, y3],
 *  the Bezier control points to match this cubic.
 *     
 */ 
VALUE dvector_make_bezier_control_points_for_cubic_in_x(VALUE dest, VALUE x0, VALUE y0, VALUE delta_x, VALUE a, VALUE b, VALUE c)
{
   x0 = rb_Float(x0);
   y0 = rb_Float(y0);
   delta_x = rb_Float(delta_x);
   a = rb_Float(a);
   b = rb_Float(b);
   c = rb_Float(c);
   return c_make_bezier_control_points_for_cubic_in_x(dest,
      NUM2DBL(x0), NUM2DBL(y0), NUM2DBL(delta_x), NUM2DBL(a), NUM2DBL(b), NUM2DBL(c));
}