scales (version 0.2.3)

zero_range: Determine if range of vector is close to zero, with a specified tolerance

Description

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 * 100 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.

Usage

zero_range(x, tol = .Machine$double.eps * 100)

Arguments

x

numeric range: vector of length 2

tol

A value specifying the tolerance. Defaults to .Machine$double.eps * 100.

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
zero_range(c(1, 1 + 99 * eps))  # TRUE
zero_range(c(1, 1 + 101 * eps)) # FALSE - Crossed the tol threshold
zero_range(c(1, 1 + 2 * eps), tol = eps) # FALSE - Changed tol

# 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
zero_range(100000 * c(1, 1 + 200 * eps))  # FALSE
zero_range(.00001 * c(1, 1 + eps))        # TRUE
zero_range(.00001 * c(1, 1 + 200 * eps))  # FALSE

# NA values
zero_range(c(1, NA))   # NA
zero_range(c(1, NaN))  # NA

# Infinite values
zero_range(c(1, Inf))     # FALSE
zero_range(c(-Inf, Inf))  # FALSE
zero_range(c(Inf, Inf))   # TRUE

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