|  | ZHANG, Ruda | March 03, 2021: 
          Use mathcal for big O notation, to distinguish from the orthogonal group.
          [69caae9] | 
      
        |  | ZHANG, Ruda | June 17, 2020: 
          Formatting. More on manifolds: integral manifold, distribution, foliation; covariant derivative along curve in submanifold; higher-order retraction.
          [c08c622] | 
      
        |  | ZHANG, Ruda | June 05, 2020: 
          More on manifolds: curvature concepts; bounds for sectional and Ricci curvature.
          [0b35b68] | 
      
        |  | ZHANG, Ruda | May 28, 2020: 
          More on manifold: geodesic, higher-order retraction, matrix manifolds, horizontal lift, C^k regular level set theorem, zero section, curvature.
          [22084b8] | 
      
        |  | ZHANG, Ruda | May 28, 2020: 
          Add optimization on manifold.
          [f036f0e] |