Package pygeodesy :: Module elliptic :: Class Elliptic |
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# Class Elliptic

      object --+
               |
    named._Named --+
                   |
                  Elliptic

Elliptic integrals and functions.

See Also: Karney's Detailed Description.

Instance Methods
__init__(self, k2=0, alpha2=0, kp2=None, alphap2=None) Constructor, specifying the `modulus` and `parameter`. |
deltaD(self, sn, cn, dn) The periodic Jahnke's incomplete elliptic integral. |
deltaE(self, sn, cn, dn) The periodic incomplete integral of the second kind. |
deltaEinv(self, stau, ctau) The periodic inverse of the incomplete integral of the second kind. |
deltaF(self, sn, cn, dn) The periodic incomplete integral of the first kind. |
deltaG(self, sn, cn, dn) Legendre's periodic geodesic longitude integral. |
deltaH(self, sn, cn, dn) Cayley's periodic geodesic longitude difference integral. |
deltaPi(self, sn, cn, dn) The periodic incomplete integral of the third kind. |
fD(self, phi_or_sn, cn=None, dn=None) Jahnke's incomplete elliptic integral in terms of Jacobi elliptic functions. |
fDelta(self, sn, cn) The `Delta` amplitude function. |
fE(self, phi_or_sn, cn=None, dn=None) The incomplete integral of the second kind in terms of Jacobi elliptic functions. |
fEd(self, deg) The incomplete integral of the second kind with the argument given in degrees. |
fEinv(self, x) The inverse of the incomplete integral of the second kind. |
fF(self, phi_or_sn, cn=None, dn=None) The incomplete integral of the first kind in terms of Jacobi elliptic functions. |
fG(self, phi_or_sn, cn=None, dn=None) Legendre's geodesic longitude integral in terms of Jacobi elliptic functions. |
fH(self, phi_or_sn, cn=None, dn=None) Cayley's geodesic longitude difference integral in terms of Jacobi elliptic functions. |
fPi(self, phi_or_sn, cn=None, dn=None) The incomplete integral of the third kind in terms of Jacobi elliptic functions. |
reset(self, k2=0, alpha2=0, kp2=None, alphap2=None) Reset the modulus and parameter. |
sncndn(self, x) The Jacobi elliptic function. |
Inherited from `named._Named`: `__copy__`, `__repr__`, `__str__`, `classof`, `copy` Inherited from `object`: `__delattr__`, `__format__`, `__getattribute__`, `__hash__`, `__new__`, `__reduce__`, `__reduce_ex__`, `__setattr__`, `__sizeof__`, `__subclasshook__`

Class Variables
| _trips_ = `13`

Properties
| alpha2 Get the parameter `alpha2` (`float`).
| alphap2 Get the complementary parameter `alphap2` (`float`).
| cD Get Jahnke's complete integral `D(k)`, defined.
| cE Get the complete integral of the second kind `E(k)`, defined.
| cG Get Legendre's complete geodesic longitude integral `G(alpha2, k)`.
| cH Get Cayley's complete geodesic longitude difference integral `H(alpha2, k)`.
| cK Get the complete integral of the first kind `K(k)`, defined.
| cKE Get the difference between the complete integrals of the first and second kinds, `K(k) − E(k)`.
| cPi Get the complete integral of the third kind `Pi(alpha2, k)`, defined.
| k2 Get the square of the modulus (`float`).
| kp2 Get the square of the complementary modulus (`float`).
Inherited from `named._Named`: `classname`, `classnaming`, `name`, `named`, `named2` Inherited from `object`: `__class__`

Method Details

### __init__(self, k2=0, alpha2=0, kp2=None, alphap2=None) (Constructor) |
Constructor, specifying the `modulus` and `parameter`. Parameters: `k2` - Modulus squared (`scalar` k^2 <= 1). `alpha2` - Parameter squared (`scalar` α^2 <= 1). `kp2` - Complementary modulus squared (`float` k'^2 >= 0). `alphap2` - Complementary parameter α'2 (`float` α'^2 >= 0). Overrides: object.__init__ Note: If only elliptic integrals of the first and second kinds are needed, then set `alpha2` = 0 (the default value); in this case, we have Π(φ, 0, k) = F(φ, k), G(φ, 0, k) = E(φ, k), and H(φ, 0, k) = F(φ, k) - D(φ, k). See Also: Method reset.

### deltaD(self, sn, cn, dn) |
The periodic Jahnke's incomplete elliptic integral. Parameters: `sn` - sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: Periodic function π D(φ, k) / (2 D(k)) - φ.

### deltaE(self, sn, cn, dn) |
The periodic incomplete integral of the second kind. Parameters: `sn` - sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: Periodic function 𝜋π E(φ, k) / (2 E(k)) - φ.

### deltaEinv(self, stau, ctau) |
The periodic inverse of the incomplete integral of the second kind. Parameters: `stau` - sinτ `ctau` - cosτ Returns: Periodic function E^−1(τ (2 E(k)/π), k) - τ.

### deltaF(self, sn, cn, dn) |
The periodic incomplete integral of the first kind. Parameters: `sn` - sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: Periodic function π F(φ, k) / (2 K(k)) - φ.

### deltaG(self, sn, cn, dn) |
Legendre's periodic geodesic longitude integral. Parameters: `sn` - sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: Periodic function π G(φ, k) / (2 G(k)) - φ.

### deltaH(self, sn, cn, dn) |
Cayley's periodic geodesic longitude difference integral. Parameters: `sn` - sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: Periodic function π H(φ, k) / (2 H(k)) - φ.

### deltaPi(self, sn, cn, dn) |
The periodic incomplete integral of the third kind. Parameters: `sn` - sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: Periodic function π Π(φ, α2, k) / (2 Π(α2, k)) - φ.

### fD(self, phi_or_sn, cn=None, dn=None) |
Jahnke's incomplete elliptic integral in terms of Jacobi elliptic functions. Parameters: `phi_or_sn` - φ or sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: D(φ, k) as though φ ∈ (−π, π], defined.

### fDelta(self, sn, cn) |
The `Delta` amplitude function. Parameters: `sn` - sinφ. `cn` - cosφ. Returns: `sqrt(1 − k2 sin2φ)`.

### fE(self, phi_or_sn, cn=None, dn=None) |
The incomplete integral of the second kind in terms of Jacobi elliptic functions. Parameters: `phi_or_sn` - φ or sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: E(φ, k) as though φ ∈ (−π, π], defined.

### fEd(self, deg) |
The incomplete integral of the second kind with the argument given in degrees. Parameters: `deg` - Angle (`degrees`). Returns: E(π deg/180, k).

### fEinv(self, x) |
The inverse of the incomplete integral of the second kind. Parameters: `x` - Argument (`float`). Returns: φ = 1 / E(`x`, k), such that E(φ, k) = `x`.

### fF(self, phi_or_sn, cn=None, dn=None) |
The incomplete integral of the first kind in terms of Jacobi elliptic functions. Parameters: `phi_or_sn` - φ or sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: F(φ, k) as though φ ∈ (−π, π], defined.

### fG(self, phi_or_sn, cn=None, dn=None) |
Legendre's geodesic longitude integral in terms of Jacobi elliptic functions. Parameters: `phi_or_sn` - φ or sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: G(φ, k) as though φ ∈ (−π, π]. Note: Legendre expresses the longitude of a point on the geodesic in terms of this combination of elliptic integrals in Exercices de Calcul Intégral, Vol 1 (1811), p 181. See Also: Geodesics in terms of elliptic integrals for the expression for the longitude in terms of this function.

### fH(self, phi_or_sn, cn=None, dn=None) |
Cayley's geodesic longitude difference integral in terms of Jacobi elliptic functions. Parameters: `phi_or_sn` - φ or sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: H(φ, k) as though φ ∈ (−π, π]. Note: Cayley expresses the longitude difference of a point on the geodesic in terms of this combination of elliptic integrals in Phil. Mag. 40 (1870), p 333. See Also: Geodesics in terms of elliptic integrals for the expression for the longitude in terms of this function.

### fPi(self, phi_or_sn, cn=None, dn=None) |
The incomplete integral of the third kind in terms of Jacobi elliptic functions. Parameters: `phi_or_sn` - φ or sinφ. `cn` - cosφ. `dn` - sqrt(1 − k2 sin2φ). Returns: Π(φ, α2, k) as though φ ∈ (−π, π].

### reset(self, k2=0, alpha2=0, kp2=None, alphap2=None) |
Reset the modulus and parameter. Parameters: `k2` - modulus squared (`float` k2 <= 1). `alpha2` - parameter (`float` α2 <= 1). `kp2` - complementary modulus squared (`float` k'2 >= 0). `alphap2` - complementary parameter α'2 (`float` α'2 >= 0). Note: The arguments must satisfy `k2` + `k2` = 1 and `alpha2` + `alphap2` = 1. No checking is done that these conditions are met to enable accuracy to be maintained, e.g., when `k` is very close to unity.

### sncndn(self, x) |
The Jacobi elliptic function. Parameters: `x` - The argument (`float`). Returns: 3-Tuple `(sn(x, k), cn(x, k), dn(x, k))`.

Property Details

### alpha2 Get the parameter `alpha2` (`float`). Get Method: alpha2(self) - Get the parameter `alpha2` (`float`). Set Method: Read_Only(self, ignored) - Throws an `AttributeError`, always.

### alphap2 Get the complementary parameter `alphap2` (`float`). Get Method: alphap2(self) - Get the complementary parameter `alphap2` (`float`). Set Method: Read_Only(self, ignored) - Throws an `AttributeError`, always.

### cD Get Jahnke's complete integral `D(k)`, defined. Get Method: cD(self) - Get Jahnke's complete integral `D(k)`, defined. Set Method: Read_Only(self, ignored) - Throws an `AttributeError`, always.

### cE Get the complete integral of the second kind `E(k)`, defined. Get Method: cE(self) - Get the complete integral of the second kind `E(k)`, defined. Set Method: Read_Only(self, ignored) - Throws an `AttributeError`, always.

### cG Get Legendre's complete geodesic longitude integral `G(alpha2, k)`. Get Method: cG(self) - Get Legendre's complete geodesic longitude integral `G(alpha2, k)`. Set Method: Read_Only(self, ignored) - Throws an `AttributeError`, always.

### cH Get Cayley's complete geodesic longitude difference integral `H(alpha2, k)`. Get Method: cH(self) - Get Cayley's complete geodesic longitude difference integral `H(alpha2, k)`. Set Method: Read_Only(self, ignored) - Throws an `AttributeError`, always.

### cK Get the complete integral of the first kind `K(k)`, defined. Get Method: cK(self) - Get the complete integral of the first kind `K(k)`, defined. Set Method: Read_Only(self, ignored) - Throws an `AttributeError`, always.

### cKE Get the difference between the complete integrals of the first and second kinds, `K(k) − E(k)`. Get Method: cKE(self) - Get the difference between the complete integrals of the first and second kinds, `K(k) − E(k)`. Set Method: Read_Only(self, ignored) - Throws an `AttributeError`, always.

### cPi Get the complete integral of the third kind `Pi(alpha2, k)`, defined. Get Method: cPi(self) - Get the complete integral of the third kind `Pi(alpha2, k)`, defined. Set Method: Read_Only(self, ignored) - Throws an `AttributeError`, always.

### k2 Get the square of the modulus (`float`). Get Method: k2(self) - Get the square of the modulus (`float`). Set Method: Read_Only(self, ignored) - Throws an `AttributeError`, always.

### kp2 Get the square of the complementary modulus (`float`). Get Method: kp2(self) - Get the square of the complementary modulus (`float`). Set Method: Read_Only(self, ignored) - Throws an `AttributeError`, always.