linksrm_convert: Parameter Conversion for Linked Stress Release Model
In PtProcess: Time Dependent Point Process Modelling

Converts parameter values between two different parameterisations (described in Details below) of the linked stress release model.

1	linksrm_convert(params, abc=TRUE)

`params`	a vector of parameter values of length n^2+2n, where n is the number of regions in the model.
`abc`	logical. If `TRUE` (default), then the input value of params is that of the `abc` parameterisation. See Details for further explanation.

If abc == TRUE, the conditional intensity for the ith region is assumed to have the form

lambda_g(t,i) = exp{ a_i + b_i*[t - sum_j c_{ij} S_j(t)]}

with params = (a_1, ..., a_n, b_1, ..., b_n, c_{11}, c_{12}, c_{13}, ..., c_{nn}).

If abc == FALSE, the conditional intensity for the ith region is assumed to have the form

lambda_g(t,i) = exp{ alpha_i + nu_i*[rho_i*t - sum_j theta_{ij} S_j(t)]}

where theta_{ii}=1 for all i, n = sqrt(length(params) + 1) - 1, and params

= (alpha_1, ..., alpha_n, nu_1, ..., nu_n, rho_1, ..., rho_n, theta_{12}, theta_{13}, ..., theta_{1n}, θ_{21}, theta_{23}, ..., theta_{n,n-1}).

A list object with the following components is returned:

`params`	vector as specified in the function call.
`a`	vector of length n as in the `abc` parameterisation.
`b`	vector of length n as in the `abc` parameterisation.
`c`	n by n matrix as in the `abc` parameterisation.
`alpha`	vector of length n as in the alternative parameterisation.
`nu`	vector of length n as in the alternative parameterisation.
`rho`	vector of length n as in the alternative parameterisation.
`theta`	n by n matrix with ones on the diagonal as in the alternative parameterisation.