The machine epsilon is the difference between 1.0 and the next number that can be represented by the machine. By default, this function uses epsilon * 1000 as the tolerance. First it scales the values so that they have a mean of 1, and then it checks if the difference between them is larger than the tolerance.

zero_range(x, tol = 1000 * .Machine$double.eps) ## Arguments x numeric range: vector of length 2 A value specifying the tolerance. ## Value logical TRUE if the relative difference of the endpoints of the range are not distinguishable from 0. ## Examples eps <- .Machine$double.eps
zero_range(c(1, 1 + eps))       # TRUE#> [1] TRUEzero_range(c(1, 1 + 99 * eps))  # TRUE#> [1] TRUEzero_range(c(1, 1 + 1001 * eps)) # FALSE - Crossed the tol threshold#> [1] FALSEzero_range(c(1, 1 + 2 * eps), tol = eps) # FALSE - Changed tol#> [1] FALSE
# Scaling up or down all the values has no effect since the values
# are rescaled to 1 before checking against tol
zero_range(100000 * c(1, 1 + eps))        # TRUE#> [1] TRUEzero_range(100000 * c(1, 1 + 1001 * eps))  # FALSE#> [1] FALSEzero_range(.00001 * c(1, 1 + eps))        # TRUE#> [1] TRUEzero_range(.00001 * c(1, 1 + 1001 * eps))  # FALSE#> [1] FALSE
# NA values
zero_range(c(1, NA))   # NA#> [1] NAzero_range(c(1, NaN))  # NA#> [1] NA
# Infinite values
zero_range(c(1, Inf))     # FALSE#> [1] FALSEzero_range(c(-Inf, Inf))  # FALSE#> [1] FALSEzero_range(c(Inf, Inf))   # TRUE#> [1] TRUE