Inhaltsangabe1 Introduction.- 2 Linear System Tools.- 3 Structural Mappings of Bilinear Transformations.- 4 Existence Conditions of H? Suboptimal Controllers.- 5 Solutions to Discrete-time Riccati Equations.- 6 Infima in Continuous-time H? Optimization.- 7 Solutions to Continuous-time H? Problem.- 8 Continuous-time H? Almost Disturbance Decoupling.- 9 Robust and Perfect Tracking of Continuous-time Systems.- 10 Infima in Discrete-time H? Optimization.- 11 Solutions to Discr,te-time H? Problem.- 12 Discrete-time H? Almost Disturbance Decoupling.- 13 Robust and Perfect Tracking of Discrete-time Systems.- 14 Design of a Hard Disk Drive Servo System.- 15 Design of a Piezoelectric Actuator System.- 16 Design of a Gyro-stabilized Mirror Targeting System.