严格正定关联函数的变量.
This reflects the `spdcf` definition of the
NGA_gpm_local glTF extension.
此类型的实例作为参数存储于 a
`CorrelationGroup`.
参数(A, α, β, T) 描述关联减少
作为三角洲时间函数的点之间:
```
spdcf(delta_t) = A_t * (alpha_t + ((1 - alpha_t)(1 + beta_t)) / (beta_t + e^(delta_t/T_t)))
```
| Name | Type | Description |
|---|---|---|
options |
Spdcf.ConstructorOptions | 描述初始化选项的对象 |
Experimental
This feature is not final and is subject to change without Cesium's standard deprecation policy.