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Neville theta functions

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Neville theta functions

In mathematics, the Neville theta functions, named after Eric Harold Neville, are defined as follows:

Contents

θ c ( z , m ) = 2 π q ( m ) 4 k = 0 ( q ( m ) ) k ( k + 1 ) cos ( 1 2 ( 2 k + 1 ) π z K ( m ) ) 1 K ( m ) 1 m 4 θ d ( z , m ) = 1 / 2 2 π ( 1 + 2 k = 1 ( q ( m ) ) k 2 cos ( π z k K ( m ) ) ) 1 K ( m ) θ n ( z , m ) = 1 / 2 π 2 ( 1 + 2 k = 1 ( 1 ) k ( q ( m ) ) k 2 cos ( π z k K ( m ) ) ) 1 1 m 4 1 K ( m ) θ s ( z , m ) = π 2 q ( m ) 4 k = 0 ( 1 ) k ( q ( m ) ) k ( k + 1 ) sin ( 1 / 2 ( 2 k + 1 ) π z K ( m ) ) 1 1 m 4 1 m 4 1 K ( m )

where:

  • K ( m ) = EllipticK ( m )
  • K ( m ) = EllipticK ( 1 m )
  • q ( m ) = e π K ( m ) / K ( m ) is the elliptic nome
  • Examples

    Substitute z = 2.5, m = 0.3 into the above definitions of Neville theta functions(using Maple) once obtain the following(consistent with results from wolfram math).

  • θ c ( 2.5 , 0.3 ) = 0.65900466676738154967
  • θ d ( 2.5 , 0.3 ) = 0.95182196661267561994
  • θ n ( 2.5 , 0.3 ) = 1.0526693354651613637
  • θ s ( 2.5 , 0.3 ) = 0.82086879524530400536
  • Symmetry

  • θ c ( z , m ) = θ c ( z , m )
  • θ d ( z , m ) = θ d ( z , m )
  • θ n ( z , m ) = θ n ( z , m )
  • θ s ( z , m ) = θ s ( z , m )
  • Implementation

    NetvilleThetaC[z,m], NevilleThetaD[z,m], NevilleThetaN[z,m], and NevilleThetaS[z,m] are built-in functions of Mathematica No such functions in Maple.

    References

    Neville theta functions Wikipedia