# Spdcf

#### new Cesium.Spdcf(options)
engine/Source/Scene/Model/Extensions/Gpm/Spdcf.js 32

Variables for a Strictly Positive-Definite Correlation Function. This reflects the `spdcf` definition of the NGA_gpm_local glTF extension. Instances of this type are stored as the parameters within a `CorrelationGroup`. Parameters (A, alpha, beta, T) describe the correlation decrease between points as a function of delta time: ``` 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 | An object describing initialization options

##### Experimental

This feature is not final and is subject to change without Cesium's standard deprecation policy.

### Members

#### readonly A : number
engine/Source/Scene/Model/Extensions/Gpm/Spdcf.js 57

In (0, 1]

#### readonly alpha : number
engine/Source/Scene/Model/Extensions/Gpm/Spdcf.js 70

In [0, 1)

#### readonly beta : number
engine/Source/Scene/Model/Extensions/Gpm/Spdcf.js 83

In [0, 10]

#### readonly T : number
engine/Source/Scene/Model/Extensions/Gpm/Spdcf.js 96

In (0, +inf)

### Type Definitions

#### Cesium.Spdcf.ConstructorOptions
engine/Source/Scene/Model/Extensions/Gpm/Spdcf.js 3

Initialization options for the Spdcf constructor

##### Properties:

Name | Type | Description
--- | --- | ---
`A` | number | The factor A, in (0, 1]
`alpha` | number | The alpha value, in [0, 1)
`beta` | number | The beta value, in [0, 10]
`T` | number | the tau value, in (0, +inf)

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