code: func (c *cubicState) fastConvergence() {
  	if c.wMax < c.wLastMax {
  		c.wLastMax = c.wMax
  		c.wMax = c.wMax * (1.0 + c.beta) / 2.0
  	} else {
  		c.wLastMax = c.wMax
  	}
  	// Recompute k as wMax may have changed.
  	c.k = math.Cbrt(c.wMax * (1 - c.beta) / c.c)
  }
docs: // fastConvergence implements the logic for Fast Convergence algorithm as
  // described in https://tools.ietf.org/html/rfc8312#section-4.6.