44 lines
1.6 KiB
Rust
44 lines
1.6 KiB
Rust
//! The Earth gravitational parameter.
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/// The gravitational parameter of the central body, in cubic kilometers per
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/// second squared.
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///
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/// Two values are offered because the workspace supports both gravity
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/// models, and the correct choice is the one that matches the source of the
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/// orbital elements. For elements derived from a two-line element set, the
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/// WGS 72 value is the one the SGP4 theory was fitted to.
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///
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/// 中心天体的引力参数，单位为立方千米每二次方秒。
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///
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/// 提供两个值是因为工作区支持两种重力模型，正确选择取决于轨道根数的来源。对
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/// 由两线根数集导出的根数，应取 WGS 72 值，即 SGP4 理论拟合所用的那一个。
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#[derive(Debug, Clone, Copy, PartialEq)]
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pub struct GravityParameter(pub f64);
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impl GravityParameter {
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/// The WGS 72 gravitational parameter, `398 600.8 km^3/s^2`.
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///
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/// WGS 72 引力参数，`398 600.8 km^3/s^2`。
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pub const WGS72: Self = Self(398_600.8);
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/// The WGS 84 gravitational parameter, `398 600.5 km^3/s^2`.
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///
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/// WGS 84 引力参数，`398 600.5 km^3/s^2`。
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pub const WGS84: Self = Self(398_600.5);
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/// Returns the value in cubic kilometers per second squared.
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///
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/// 返回该值，单位为立方千米每二次方秒。
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pub const fn value(self) -> f64 {
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self.0
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}
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/// Returns the square root of the parameter, in kilometers to the three
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/// halves per second.
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///
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/// 返回该参数的平方根，单位为千米的三分之二次方每秒。
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pub fn sqrt(self) -> f64 {
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self.0.sqrt()
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}
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}
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