Description
Return eccentricity squared f times (2-f), and its nonnegative square root for eccentricity.
An oblate reference ellipsoid describes its shape through semiaxes, flattening, and eccentricity. Curvature varies with geodetic latitude, and prime-vertical and meridional radii describe different local directions.
Return eccentricity squared f times (2-f), and its nonnegative square root for eccentricity.
When to use this tool
Use Oblate Spheroid Flattening Eccentricity Crosswalk when you need an ellipsoid-shape crosswalk or local curvature term.
How to use the tool and how it works
- Enter flattening. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read eccentricitySquared, eccentricity. Use the output convention below.
Require flattening f within [0, 1). Return eccentricity squared f times (2-f), and its nonnegative square root for eccentricity.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| flattening | Dimensionless (a-b)/a, not inverse flattening. | Required. Finite number; minimum 0; strictly below 1. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| eccentricitySquared | Eccentricity Squared | Required. Finite number. |
| eccentricity | Eccentricity | Required. Finite number. |
{
"input": {
"flattening": 0.2
},
"output": {
"eccentricitySquared": 0.36000000000000004,
"eccentricity": 0.6000000000000001
}
}Limitations and assumptions
- Flattening means (a-b)/a, not inverse flattening. Both outputs are dimensionless; no particular reference ellipsoid or semiaxis values are selected.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Choose a named reference ellipsoid and a complete geodetic method for position or distance work. Distinguish eccentricity from its square and flattening from inverse flattening.
References
Similar or alternative tools
- Ellipsoid Prime Vertical Radius Term
Return semimajor divided by the square root of 1 minus eccentricitySquared times sine-squared latitude.
- Ellipsoid Meridional Radius Term
Return semimajor times (1-e²) divided by (1-e² sin² latitude) to the power 3/2.