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math.IsNearlyEqual

  boolean math.IsNearlyEqual( number a, number b, number tolerance = 1e-8 )
View Source 2025.01.22 Search Github

Description

Checks if two floating point numbers are nearly equal.

This is useful to mitigate accuracy issues in floating point numbers. See examples below.

Arguments

1 number a
The first number to compare.
2 number b
The second number to compare.
3 number tolerance = 1e-8
The maximum difference between the two numbers to consider them equal.

Returns

1 boolean
True if the difference between the two numbers is less than or equal to the tolerance.

Example

Shows the problem known as a floating-point error, due to the limited precision of decimal numbers in hardware.

print( 0.1 + 0.2 == 0.3 ) -- Which is mathematically true. print( string.format( "%.32f", 0.1 + 0.2 ) ) -- Outputs the result with up to 32 decimal numbers.
Output:
false 0.30000000000000004440892098500626

Example

Shows the workaround using math.IsNearlyEqual().

print( math.IsNearlyEqual( 0.1 + 0.2, 0.3 ) ) print( string.format( "%.32f", 0.1 + 0.2 ) )
Output:
true 0.30000000000000004440892098500626

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