Petal (left) and intra-petal (right) standard deviations expressed in radians without modal gain compensation (integrator gain set to 1, in blue) and with the use of CLOSE algorithm (null setpoint and learning factor (q⁺ = 1/200, q⁻ = 1/100), in orange). The component of fitting and aliasing errors for a triangular actuator grid is shown as the dashed grey line. Shaded areas: ±1σ error bars.