keep list pos.

[01] 2-Dimensional Linear Autonomous System of 1 Order   1. One of the eigenvalues is 0:   2. There are two eigenvalues with different signs:   3. There are two eigenvalues and both are positive 1:   4. There are two eigenvalues and both are positive 2:   5. There are two eigenvalues and both are negative:   6. The eigenvalues are double root, matrix A is diagonalizable:   7. The eigenvalues are double root, matrix A is not diagonalizable:   8. The eigenvalues are purely imaginary:   9. The eigenvalues have both real and imaginary parts: [02] 2-Dimensional Linear Autonomous System of 2 Order   1. Node-Saddle Point Type:   2. Degenerate Node-Saddle Point Type:   3. Double Elliptic Type:   4. Triple Crossing Type:   5. Node Type 2:   6. Parabolic Type: [03] High-order Simultaneous Autonomous System:   1. Homogeneous Autonomous System with periodic solution:   2. Homogeneous Autonomous System with eight parabolic sectors:   3. Homogeneous Autonomous System with compound sectors:   4. Vinograd's Autonomous System: [04] 2-Dimensional Autonomous System Examples:   1. Autonomous System with periodic equilibrium points on x-axis:   2. Autonomous System with 8 equilibrium points on the circumference:   3. Autonomous system with periodic equilibrium points on a plane:   4. Limit Cycle 1:   5. Limit Cycle 2: von del Pol:   6. Limit Cycle 3: Lemniscate:   7. Limit Cycle 4: for pure imaginary eigenvalues 1   8. Limit Cycle 5: for pure imaginary eigenvalues 2   9. Hamilton System 1: Cassini oval   10. Hamilton System 2: folium of Descartes   11. Hamilton System 3: derivatives of "folium of Descartes"   12. Hamilton System 4: for trigonometric functions [99] User defined Equations   0. User defined Equations   1. sample 1   2. sample 2   3. sample 3   4. sample 4   5. sample 5