# Calculates prior variances of coefficients in a spectral GP object

### Description

Calculates the prior variances of the spectral coefficients in a GP
object. The variances are based on the spectral density function
chosen in `gp`

and the
correlation function parameters supplied.

### Usage

1 2 | ```
## S3 method for class 'gp'
calc.variances(object,...)
``` |

### Arguments

`object` |
A GP object, created by |

`...` |
Other arguments. |

### Details

This function is an internal function not meant to be called by the user.
The prior variances for each coefficient are calculated based on the
frequency of the corresponding basis function, the spectral density
function, the parameters of the spectral density/correlation
function, and the (optional) coefficient variance parameter.
The function creates `variances`

, a matrix of
variances corresponding to `coeff`

, the matrix of coefficients.

### Value

The function modifies the GP object, which is essentially a pointer (an R environment in this case), so NULL is returned.

### Author(s)

Christopher Paciorek paciorek@alumni.cmu.edu

### References

Type 'citation("spectralGP")' for references.

### See Also

`gp`

, `propose.coeff.gp`

, `simulate.gp`

, `logdensity.gp`

, `change.param.gp`