dot-epsilon_matrix: .epsilon_matrix
In sGBJ: Survival Extension of the Generalized Berk-Jones Test

Compute the epsilon matrix by permutation for the sGBJ_scores() function.

1	.epsilon_matrix(Z, nperm, surv, factor_matrix, covariates = NULL, dat)

`Z`	the score vector returned by `.survival_scores()` function.
`nperm`	number of permutations performed to estimate the `epsilon` matrix. Default is `300`.
`surv`	a `Surv` object of length `n`
`factor_matrix`	a `n x p` `data.frame` of the expression for the particular gene set of interest being tested
`covariates`	a `n x l` matrix of the covariates to adjust upon. Default is `NULL`
`dat`	data used to fit survival model returned by `.survival_scores()` function.