Macro float_eq::assert_float_eq

macro_rules! assert_float_eq {
    ($left:expr, $right:expr, $eq1:ident <= $max_diff_1:expr, $eq2:ident <= $max_diff_2:expr, $eq3:ident <= $max_diff_3:expr) => { ... };
    ($left:expr, $right:expr, $eq1:ident <= $max_diff_1:expr, $eq2:ident <= $max_diff_2:expr) => { ... };
    ($left:expr, $right:expr, $eq1:ident <= $max_diff_1:expr) => { ... };
    ($left:expr, $right:expr, $($eq:ident <= $max_diff:expr,)+) => { ... };
    ($left:expr, $right:expr, $eq1:ident <= $max_diff_1:expr, $eq2:ident <= $max_diff_2:expr, $eq3:ident <= $max_diff_3:expr, $($arg:tt)+) => { ... };
    ($left:expr, $right:expr, $eq1:ident <= $max_diff_1:expr, $eq2:ident <= $max_diff_2:expr, $($arg:tt)+) => { ... };
    ($left:expr, $right:expr, $eq1:ident <= $max_diff_1:expr, $($arg:tt)+) => { ... };
}

Asserts that two floating point expressions are equal to each other.

Comparisons are applied in order from left to right, shortcutting to return early if a positive result is found.

• abs <= max_diff is an absolute epsilon comparison.
• rmax <= max_diff is a relative epsilon comparison.
• rmin <= max_diff is a relative epsilon comparison.
• r1st <= max_diff is a relative epsilon comparison.
• r2nd <= max_diff is a relative epsilon comparison.
• ulps <= max_diff is an ULPs comparison.

When comparing composite types, variants that use a uniform max_diff value across all fields are also available:

• abs_all <= max_diff is an absolute epsilon comparison.
• rmax_all <= max_diff is a relative epsilon comparison.
• rmin_all <= max_diff is a relative epsilon comparison.
• r1st_all <= max_diff is a relative epsilon comparison.
• r2nd_all <= max_diff is a relative epsilon comparison.
• ulps_all <= max_diff is an ULPs comparison.

On panic, this macro will print the values of the expressions with their debug representations, with additional information from the comparison operations (using AssertFloatEq and AssertFloatEqAll).

Like assert!, this macro has a second form, where a custom panic message can be provided.

Examples

let a: f32 = 4.0;
let b: f32 = 4.000_002_5;

assert_float_eq!(a, 3.999_999_6, rmax <= 2.0 * f32::EPSILON);
assert_float_eq!(a - b, 0.0, abs <= 0.000_01);
assert_float_eq!(a, b, abs <= 0.000_01, ulps <= 10);

assert_float_eq!(a - b, 0.0, abs <= 0.000_01, ulps <= 10, "Checking that {} == {}", a, b);