check_stop: Check if stopping criterion satisified
In r-glennie/fmin: Minimize a multivariate function

Check if stopping criterion satisified

1	check_stop(theta, fval, g, delta, iter, tol, maxit, conv = FALSE)

`theta`	current parameters
`fval`	current function value
`g`	gradient vector
`delta`	step vector
`iter`	current iteration number
`tol`	tolerance for tests
`maxit`	maximum number of iterations
`conv`	if TRUE return whether convergence criterion, not just stopping criteria are satisified