Takes parameters for a multivariate normal distribution and observed values
to calculate the conditional distribution for the unobserved values.
     
    
    Usage
    get_conditional_parameters(pars, values)
 
     
    
    Arguments
- pars
 
a list with elements mu and sigma defining the mean vector and
covariance matrix respectively.
 
- values
 
a vector of observed values to condition on, must be same length as pars$mu.
Missing values must be represented by an NA.
 
 
    
    Value
    A list with the conditional distribution parameters: