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  2. Curvature - Wikipedia

    en.wikipedia.org/wiki/Curvature

    Animation of the curvature and the acceleration vector T′(s) As in the case of curves in two dimensions, the curvature of a regular space curve C in three dimensions (and higher) is the magnitude of the acceleration of a particle moving with unit speed along a curve. Thus if γ(s) is the arc-length parametrization of C then the unit tangent ...

  3. Total curvature - Wikipedia

    en.wikipedia.org/wiki/Total_curvature

    The total curvature of a closed curve is always an integer multiple of 2 π, where N is called the index of the curve or turning number – it is the winding number of the unit tangent vector about the origin, or equivalently the degree of the map to the unit circle assigning to each point of the curve, the unit velocity vector at that point.

  4. 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 f {\displaystyle f} , which are solutions to the equation f ( x ) = 0 {\displaystyle f(x)=0} .

  5. 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 ...

  6. Normal (geometry) - Wikipedia

    en.wikipedia.org/wiki/Normal_(geometry)

    A normal vector of length one is called a unit normal vector. A curvature vector is a normal vector whose length is the curvature of the object. Multiplying a normal vector by −1 results in the opposite vector, which may be used for indicating sides (e.g., interior or exterior).

  7. Radius of curvature - Wikipedia

    en.wikipedia.org/wiki/Radius_of_curvature

    Radius of curvature and center of curvature. In differential geometry, the radius of curvature, R, is the reciprocal of the curvature. For a curve, it equals the radius of the circular arc which best approximates the curve at that point. For surfaces, the radius of curvature is the radius of a circle that best fits a normal section or ...

  8. Torsion of a curve - Wikipedia

    en.wikipedia.org/wiki/Torsion_of_a_curve

    Animation of the torsion and the corresponding rotation of the binormal vector. Let r be a space curve parametrized by arc length s and with the unit tangent vector T.If the curvature κ of r at a certain point is not zero then the principal normal vector and the binormal vector at that point are the unit vectors

  9. Ricci curvature - Wikipedia

    en.wikipedia.org/wiki/Ricci_curvature

    Indeed, if is a vector of unit length on a Riemannian -manifold, then ⁡ (,) is precisely () times the average value of the sectional curvature, taken over all the 2-planes containing . There is an ( n − 2 ) {\displaystyle (n-2)} -dimensional family of such 2-planes, and so only in dimensions 2 and 3 does the Ricci tensor determine the full ...