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  2. Conjugate diameters - Wikipedia

    en.wikipedia.org/wiki/Conjugate_diameters

    For an ellipse, two diameters are conjugate if and only if the tangent line to the ellipse at an endpoint of one diameter is parallel to the other diameter. Each pair of conjugate diameters of an ellipse has a corresponding tangent parallelogram, sometimes called a bounding parallelogram (skewed compared to a bounding rectangle).

  3. Ellipse - Wikipedia

    en.wikipedia.org/wiki/Ellipse

    An ellipse (red) obtained as the intersection of a cone with an inclined plane. Ellipse: notations Ellipses: examples with increasing eccentricity. In mathematics, an ellipse is a plane curve surrounding two focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant.

  4. Parallelogram - Wikipedia

    en.wikipedia.org/wiki/Parallelogram

    For an ellipse, two diameters are said to be conjugate if and only if the tangent line to the ellipse at an endpoint of one diameter is parallel to the other diameter. Each pair of conjugate diameters of an ellipse has a corresponding tangent parallelogram , sometimes called a bounding parallelogram, formed by the tangent lines to the ellipse ...

  5. Derivation of the conjugate gradient method - Wikipedia

    en.wikipedia.org/wiki/Derivation_of_the...

    Each edge of the bounding parallelogram is parallel to one of the diameters. The concept of conjugate directions came from classical geometry of ellipse. For an ellipse, two semi-axes center are mutually conjugate with respect to the ellipse iff the lines are parallel to the tangent bounding parallelogram, as pictured.

  6. Conic section - Wikipedia

    en.wikipedia.org/wiki/Conic_section

    Parallelogram method for constructing an ellipse. Another method, based on Steiner's construction and which is useful in engineering applications, is the parallelogram method, where a conic is constructed point by point by means of connecting certain equally spaced points on a horizontal line and a vertical line. [58]

  7. Hyperbola - Wikipedia

    en.wikipedia.org/wiki/Hyperbola

    the tangent = + at point (, /). A ... This is the equation of an ellipse (< ... The Steiner generation is sometimes called a parallelogram method because one can use ...

  8. Jacobi elliptic functions - Wikipedia

    en.wikipedia.org/wiki/Jacobi_elliptic_functions

    Plot of the Jacobi ellipse (x 2 + y 2 /b 2 = 1, b real) and the twelve Jacobi elliptic functions pq(u,m) for particular values of angle φ and parameter b. The solid curve is the ellipse, with m = 1 − 1/b 2 and u = F(φ,m) where F(⋅,⋅) is the elliptic integral of the first kind (with parameter =). The dotted curve is the unit circle.

  9. Elliptic geometry - Wikipedia

    en.wikipedia.org/wiki/Elliptic_geometry

    Kepler and Desargues used the gnomonic projection to relate a plane σ to points on a hemisphere tangent to it. With O the center of the hemisphere, a point P in σ determines a line OP intersecting the hemisphere, and any line L ⊂ σ determines a plane OL which intersects the hemisphere in half of a great circle. The hemisphere is bounded by ...