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  2. Upper half-plane - Wikipedia

    en.wikipedia.org/wiki/Upper_half-plane

    The uniformization theorem for surfaces states that the upper half-plane is the universal covering space of surfaces with constant negative Gaussian curvature. The closed upper half-plane is the union of the upper half-plane and the real axis. It is the closure of the upper half-plane.

  3. Half-space (geometry) - Wikipedia

    en.wikipedia.org/wiki/Half-space_(geometry)

    A half-space can be either open or closed. An open half-space is either of the two open sets produced by the subtraction of a hyperplane from the affine space. A closed half-space is the union of an open half-space and the hyperplane that defines it. The open (closed) upper half-space is the half-space of all (x 1, x 2, ..., x n) such that x n > 0

  4. Modular group - Wikipedia

    en.wikipedia.org/wiki/Modular_group

    Two points in the upper half-plane give isomorphic elliptic curves if and only if they are related by a transformation in the modular group. Thus, the quotient of the upper half-plane by the action of the modular group is the so-called moduli space of elliptic curves: a space whose points describe isomorphism classes of elliptic curves. This is ...

  5. Hilbert transform - Wikipedia

    en.wikipedia.org/wiki/Hilbert_transform

    For an analytic function in the upper half-plane, the Hilbert transform describes the relationship between the real part and the imaginary part of the boundary values. That is, if f ( z ) is analytic in the upper half complex plane { z : Im{ z } > 0} , and u ( t ) = Re{ f ( t + 0· i )} , then Im{ f ( t + 0· i )} = H( u )( t ) up to an ...

  6. Jordan's lemma - Wikipedia

    en.wikipedia.org/wiki/Jordan's_lemma

    The path C is the concatenation of the paths C 1 and C 2.. Jordan's lemma yields a simple way to calculate the integral along the real axis of functions f(z) = e i a z g(z) holomorphic on the upper half-plane and continuous on the closed upper half-plane, except possibly at a finite number of non-real points z 1, z 2, …, z n.

  7. Poincaré half-plane model - Wikipedia

    en.wikipedia.org/wiki/Poincaré_half-plane_model

    The metric of the model on the half-plane, { , >}, is: = + ()where s measures the length along a (possibly curved) line. The straight lines in the hyperbolic plane (geodesics for this metric tensor, i.e., curves which minimize the distance) are represented in this model by circular arcs perpendicular to the x-axis (half-circles whose centers are on the x-axis) and straight vertical rays ...

  8. Schwarz–Christoffel mapping - Wikipedia

    en.wikipedia.org/wiki/Schwarz–Christoffel_mapping

    In complex analysis, a Schwarz–Christoffel mapping is a conformal map of the upper half-plane or the complex unit disk onto the interior of a simple polygon.Such a map is guaranteed to exist by the Riemann mapping theorem (stated by Bernhard Riemann in 1851); the Schwarz–Christoffel formula provides an explicit construction.

  9. Nevanlinna function - Wikipedia

    en.wikipedia.org/wiki/Nevanlinna_function

    In mathematics, in the field of complex analysis, a Nevanlinna function is a complex function which is an analytic function on the open upper half-plane and has a non-negative imaginary part. A Nevanlinna function maps the upper half-plane to itself or a real constant, [1] but is not necessarily injective or surjective.