Package pygeodesy :: Module datum |
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# Module datum

DEPRECATED, use module datums or ellipsoids instead.

Version: 20.08.25

Classes
| Curvature2Tuple 2-Tuple `(meridional, prime_vertical)` of radii of curvature, both in `meter`.
| Datum Ellipsoid and transform parameters for an earth model.
| Ellipsoid Ellipsoid with equatorial and polar radius, flattening, inverse flattening and other, often used, cached attributes, supporting spherical and oblate and prolate ellipsoidal models.
| Ellipsoid2 Like Ellipsoid, but specified by equatorial radius and flattening.
| Transform Helmert transformation.
| a_f2Tuple 2-Tuple `(a, f)` specifying an ellipsoid by equatorial radius (`meter`) and scalar flattening.

Functions
a_b2f(a, b) Return `f`, the flattening for a given equatorial and polar radius. |
a_b2f2(a, b) Return `f2`, the 2nd flattening for a given equatorial and polar radius. |
a_b2f_(a, b) Return `f_`, the inverse flattening for a given equatorial and polar radius. |
a_b2n(a, b) Return `n`, the rd flattening for a given equatorial and polar radius. |
a_f2b(a, f) Return `b`, the polar radius for a given equatorial radius and flattening. |
a_f_2b(a, f_) Return `b`, the polar radius for a given equatorial radius and inverse flattening. |
b_f2a(b, f) Return `a`, the equatorial radius for a given polar radius and flattening. |
b_f_2a(b, f_) Return `a`, the equatorial radius for a given polar radius and inverse flattening. |
f2e2(f) Return `e2`, the eccentricity squared for a given flattening. |
f2e22(f) Return `e22`, the 2nd eccentricity squared for a given flattening. |
f2e32(f) Return `e32`, the 3rd eccentricity squared for a given flattening. |
f2f2(f) Return `f2`, the 2nd flattening for a given flattening. |
f2f_(f) Return `f_`, the inverse flattening for a given flattening. |
f2n(f) Return `n`, the 3rd flattening for a given flattening. |
f_2f(f_) Return `f`, the flattening for a given inverse flattening. |
n2e2(n) Return `e2`, the eccentricity squared for a given 3rd flattening. |
n2f(n) Return `f`, the flattening for a given 3rd flattening. |

Variables
| Datums = `Datums.BD72: Datum(name='BD72', ellipsoid=Ellipsoids.`...``
| Ellipsoids = `Ellipsoids.Airy1830: Ellipsoid(name='Airy1830', a`...``
| R_FM = `6371000.0`
| R_KM = `6371.008771415`
| R_M = `6371008.771415`
| R_MA = `6378137.0`
| R_MB = `6356752.0`
| R_NM = `3440.06953446921`
| R_SM = `3958.753395372691`
| R_VM = `6366707.0194937`
| Transforms = `Transforms.BD72: Transform(name='BD72', tx=106.86`...``

Function Details

### a_b2f (a, b) |
Return `f`, the flattening for a given equatorial and polar radius. Arguments: `a` - Equatorial (major) radius (`scalar` > 0). `b` - Polar (minor) radius (`scalar` > 0). Returns: The flattening (`float` or `0`), (a - b) / a. Note: The result is negative for prolate or `0` for near-spherical ellipsoids.

### a_b2f2 (a, b) |
Return `f2`, the 2nd flattening for a given equatorial and polar radius. Arguments: `a` - Equatorial (major) radius (`scalar` > 0). `b` - Polar (minor) radius (`scalar` > 0). Returns: The 2nd flattening (`float` or `0`), (a - b) / b. Note: The result is negative for prolate or `0` for near-spherical ellipsoids.

### a_b2f_ (a, b) |
Return `f_`, the inverse flattening for a given equatorial and polar radius. Arguments: `a` - Equatorial (major) radius (`scalar` > 0). `b` - Polar (minor) radius (`scalar` > 0). Returns: The inverse flattening (`float` or `0`), a / (a - b). Note: The result is negative for prolate or `0` for near-spherical ellipsoids.

### a_b2n (a, b) |
Return `n`, the rd flattening for a given equatorial and polar radius. Arguments: `a` - Equatorial (major) radius (`scalar` > 0). `b` - Polar (minor) radius (`scalar` > 0). Returns: The 3rd flattening (`float` or `0`), (a - b) / (a + b). Note: The result is negative for prolate or `0` for near-spherical ellipsoids.

### a_f2b (a, f) |
Return `b`, the polar radius for a given equatorial radius and flattening. Arguments: `a` - Equatorial (major) radius (`scalar` > 0). `f` - Flattening (`scalar` < 1). Returns: The polar (minor) radius (`float`), a * (1 - f).

### a_f_2b (a, f_) |
Return `b`, the polar radius for a given equatorial radius and inverse flattening. Arguments: `a` - Equatorial (major) radius (`scalar` > 0). `f_` - Inverse flattening (`scalar` >>> 1). Returns: The polar (minor) radius (`float`), a * (f_ - 1) / f_.

### b_f2a (b, f) |
Return `a`, the equatorial radius for a given polar radius and flattening. Arguments: `b` - Polar (minor) radius (`scalar` > 0). `f` - Flattening (`scalar` < 1). Returns: The equatorial (major) radius (`float`), b / (1 - f).

### b_f_2a (b, f_) |
Return `a`, the equatorial radius for a given polar radius and inverse flattening. Arguments: `b` - Polar (minor) radius (`scalar` > 0). `f_` - Inverse flattening (`scalar` >>> 1). Returns: The equatorial (major) radius (`float`), b * f_ / (f_ - 1).

### f2e2 (f) |
Return `e2`, the eccentricity squared for a given flattening. Arguments: `f` - Flattening (`scalar` < 1). Returns: The (1st) eccentricity squared (`float` < 1), f * (2 - f). Note: The result is negative for prolate or `0` for near-spherical ellipsoids. See Also: Eccentricity conversions and Flattening.

### f2e22 (f) |
Return `e22`, the 2nd eccentricity squared for a given flattening. Arguments: `f` - Flattening (`scalar` < 1). Returns: The 2nd eccentricity squared (`float` > -1 or `INF`), f * (2 - f) / (1 - f)**2. Note: The result is negative for prolate or `0` for near-spherical ellipsoids. See Also: Eccentricity conversions.

### f2e32 (f) |
Return `e32`, the 3rd eccentricity squared for a given flattening. Arguments: `f` - Flattening (`scalar` < 1). Returns: The 3rd eccentricity squared (`float`), f * (2 - f) / (1 + (1 - f)**2). Note: The result is negative for prolate or `0` for near-spherical ellipsoids. See Also: Eccentricity conversions.

### f2f2 (f) |
Return `f2`, the 2nd flattening for a given flattening. Arguments: `f` - Flattening (`scalar` < 1). Returns: The 2nd flattening (`float` or `INF`), f / (1 - f). Note: The result is negative for prolate or `0` for near-spherical ellipsoids. See Also: Eccentricity conversions and Flattening.

### f2f_ (f) |
Return `f_`, the inverse flattening for a given flattening. Arguments: `f` - Flattening (`scalar` < 1). Returns: The inverse flattening (`float` or `0`), 1 / f. Note: The result is negative for prolate or `0` for near-spherical ellipsoids.

### f2n (f) |
Return `n`, the 3rd flattening for a given flattening. Arguments: `f` - Flattening (`scalar` < 1). Returns: The 3rd flattening (-1 < `float` < 1), f / (2 - f). Note: The result is negative for prolate or `0` for near-spherical ellipsoids. See Also: Eccentricity conversions and Flattening.

### f_2f (f_) |
Return `f`, the flattening for a given inverse flattening. Arguments: `f_` - Inverse flattening (`scalar` >>> 1). Returns: The flattening (`float` or `0`), 1 / f_. Note: The result is negative for prolate or `0` for near-spherical ellipsoids.

### n2e2 (n) |
Return `e2`, the eccentricity squared for a given 3rd flattening. Arguments: `n` - The 3rd flattening (-1 < `scalar` < 1). Returns: The (1st) eccentricity squared (`float` or -INF), 4 * n / (1 + n)**2. Note: The result is negative for prolate or `0` for near-spherical ellipsoids. See Also: Flattening.

### n2f (n) |
Return `f`, the flattening for a given 3rd flattening. Arguments: `n` - The 3rd flattening (-1 <= `scalar` <= 1). Returns: The flattening (`float` or -INF), 2 * n / (1 + n). See Also: Eccentricity conversions and Flattening.

Variables Details

  ### Datums Value:
      Datums.BD72: Datum(name='BD72', ellipsoid=Ellipsoids.Intl1924, transfo
      rm=Transforms.BD72),
      Datums.DHDN: Datum(name='DHDN', ellipsoid=Ellipsoids.Bessel1841, trans
      form=Transforms.DHDN),
      Datums.ED50: Datum(name='ED50', ellipsoid=Ellipsoids.Intl1924, transfo
      rm=Transforms.ED50),
      Datums.GDA2020: Datum(name='GDA2020', ellipsoid=Ellipsoids.GRS80, tran
      sform=Transforms.WGS84),
      ...

  ### Ellipsoids Value:
      Ellipsoids.Airy1830: Ellipsoid(name='Airy1830', a=6377563.396, b=63562
      56.90923729, f_=299.3249646, f=0.00334085, f2=0.00335205, n=0.00167322
      , e=0.08167337, e2=0.00667054, e22=0.00671533, e32=0.00334643, L=10001
      126.0807165, R1=6370461.23374576, R2=6370459.65470808, R3=6370453.3099
      4572),
      Ellipsoids.AiryModified: Ellipsoid(name='AiryModified', a=6377340.189,
       b=6356034.44793853, f_=299.3249646, f=0.00334085, f2=0.00335205, n=0.
      00167322, e=0.08167337, e2=0.00667054, e22=0.00671533, e32=0.00334643,
      ...

  ### Transforms Value:
      Transforms.BD72: Transform(name='BD72', tx=106.86863, ty=-52.29778, tz
      =103.72389, rx=-0, ry=-0, rz=-0.00001, s=1.2727, s1=1, sx=-0.33657, sy
      =-0.45696, sz=-1.84218),
      Transforms.Bessel1841: Transform(name='Bessel1841', tx=-582, ty=-105,
      tz=-414, rx=-0.00001, ry=-0, rz=0.00001, s=-8.3, s1=0.99999, sx=-1.04,
       sy=-0.35, sz=3.08),
      Transforms.Clarke1866: Transform(name='Clarke1866', tx=8, ty=-160, tz=
      -176, rx=0, ry=0, rz=0, s=0, s1=1, sx=0, sy=0, sz=0),
      ...