match_arg()
match_arg( arg = "lo", choices = c("loooong", "else"), several.ok = FALSE, none.ok = FALSE ) #> [1] "loooong"
check_covariance_matrix()
check_covariance_matrix( matrix(c(1, 2, 2, 1), nrow = 2) * -1 ) #> [1] "Must have positive eigenvalues only"
check_correlation_matrix()
check_correlation_matrix( matrix(c(1, 0, 0, 0), nrow = 2) ) #> [1] "Must have ones on the diagonal"
check_transition_probability_matrix()
check_correlation_matrix( matrix(c(1, 1, 0, 1), nrow = 2) ) #> [1] "Must be symmetric"
check_probability_vector()
check_probability_vector( 1:5 / sum(1:5), len = 4 ) #> [1] "Must have length 4, but has length 5"