Comparisons

The float_comparisons.hpp library is a simple set of functions for performing approximate numerical comparisons. There are separate functions for performing comparisons using absolute bounds and relative bounds. Absolute comparison checks are prefixed with abs_ and relative checks are prefixed with rel_.

The bool_comparisons.hpp library additionally contains an XOR operator.

The intent of the library is to improve readability of code and reduce likelihood of typographical errors when using numerical and boolean comparisons.

Target use cases

The approximate comparisons are intended to be used to check whether two numbers lie within some absolute or relative interval. The exclusive_or function will test whether two values cast to different boolean values.

Assumptions

• The approximate comparisons all take an epsilon parameter. The value of this parameter must be >= 0.
• The library is only intended to be used with floating point types. A static assertion will be thrown if the library is used with a non-floating point type.

Example Usage

#include "autoware_auto_common/common/bool_comparisons.hpp"
#include "autoware_auto_common/common/float_comparisons.hpp"

#include <iostream>

// using-directive is just for illustration; don't do this in practice
using namespace autoware::common::helper_functions::comparisons;

static constexpr auto epsilon = 0.2;
static constexpr auto relative_epsilon = 0.01;

std::cout << exclusive_or(true, false) << "\n";
// Prints: true

std::cout << rel_eq(1.0, 1.1, relative_epsilon)) << "\n";
// Prints: false

std::cout << approx_eq(10000.0, 10010.0, epsilon, relative_epsilon)) << "\n";
// Prints: true

std::cout << abs_eq(4.0, 4.2, epsilon) << "\n";
// Prints: true

std::cout << abs_ne(4.0, 4.2, epsilon) << "\n";
// Prints: false

std::cout << abs_eq_zero(0.2, epsilon) << "\n";
// Prints: false

std::cout << abs_lt(4.0, 4.25, epsilon) << "\n";
// Prints: true

std::cout << abs_lte(1.0, 1.2, epsilon) << "\n";
// Prints: true

std::cout << abs_gt(1.25, 1.0, epsilon) << "\n";
// Prints: true

std::cout << abs_gte(0.75, 1.0, epsilon) << "\n";
// Prints: false