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  2. Newton's method in optimization - Wikipedia

    en.wikipedia.org/wiki/Newton's_method_in...

    Newton's method uses curvature information (i.e. the second derivative) to take a more direct route. In calculus, Newton's method (also called Newton–Raphson) is an iterative method for finding the roots of a differentiable function, which are solutions to the equation =.

  3. Principal curvature - Wikipedia

    en.wikipedia.org/wiki/Principal_curvature

    The product k 1 k 2 of the two principal curvatures is the Gaussian curvature, K, and the average (k 1 + k 2)/2 is the mean curvature, H. If at least one of the principal curvatures is zero at every point, then the Gaussian curvature will be 0 and the surface is a developable surface. For a minimal surface, the mean curvature is zero at every ...

  4. Mean curvature - Wikipedia

    en.wikipedia.org/wiki/Mean_curvature

    For a surface defined in 3D space, the mean curvature is related to a unit normal of the surface: = ^ where the normal chosen affects the sign of the curvature. The sign of the curvature depends on the choice of normal: the curvature is positive if the surface curves "towards" the normal.

  5. Liouville's equation - Wikipedia

    en.wikipedia.org/wiki/Liouville's_equation

    By using the change of variables log f ↦ u, another commonly found form of Liouville's equation is obtained: =. Other two forms of the equation, commonly found in the literature, [4] are obtained by using the slight variant 2 log f ↦ u of the previous change of variables and Wirtinger calculus: [5] = ¯ =.

  6. Hessian matrix - Wikipedia

    en.wikipedia.org/wiki/Hessian_matrix

    The determinant of the Hessian matrix, when evaluated at a critical point of a function, is equal to the Gaussian curvature of the function considered as a manifold. The eigenvalues of the Hessian at that point are the principal curvatures of the function, and the eigenvectors are the principal directions of curvature.

  7. Sectional curvature - Wikipedia

    en.wikipedia.org/wiki/Sectional_curvature

    Alternatively, the sectional curvature can be characterized by the circumference of small circles. Let be a two-dimensional plane in .Let () for sufficiently small > denote the image under the exponential map at of the unit circle in , and let () denote the length of ().

  8. Mean curvature flow - Wikipedia

    en.wikipedia.org/wiki/Mean_curvature_flow

    The mean curvature flow extremalizes surface area, and minimal surfaces are the critical points for the mean curvature flow; minima solve the isoperimetric problem. For manifolds embedded in a Kähler–Einstein manifold , if the surface is a Lagrangian submanifold , the mean curvature flow is of Lagrangian type, so the surface evolves within ...

  9. Winding number - Wikipedia

    en.wikipedia.org/wiki/Winding_number

    A point's winding number with respect to a polygon can be used to solve the point in polygon (PIP) problem – that is, it can be used to determine if the point is inside the polygon or not. Generally, the ray casting algorithm is a better alternative to the PIP problem as it does not require trigonometric functions, contrary to the winding ...