Helper function to calculate the standard errors of standard deviations and
correlations from a MIXL model. Together, all the helper functions and the
four functions fn_se_var, fn_se_cov,
fn_se_corr and fn_se_std, is an application
of the Delta method. The helper functions are for internal use only and are
not exported.
fn_1(a, L)An integer indicating the row position of the random parameter in the asymptotic variance-covariance matrix
The lower cholesky matrix
http://www.stephanehess.me.uk/software.html Daly, A. J., Hess, S., & de Jong, G., 2012, Calculating errors for measures derived from choice modelling estimates, Transportation Research Part B, 46(2):333-341