nearlyEqual

nearlyEqual( 
n_val1 n_val2 
[ f_relTolerance [f_absTolerance] ] 
) 
=> t / nil

Description

Checks whether one value (n_val1) is approximately equal to another value (n_val2).

Arguments

n_val1 n_val2	The values that need to be checked.
f_relTolerance	The relative tolerance or the amount of error allowed, relative to the larger absolute value of n_val1 or n_val2. It must be greater than 0. The default tolerance is 1e-9, which ensures that the two values are the same within about 9 decimal digits. To set a tolerance of 5%, for example, the pass tolerance must be equal to 0.05.
f_absTolerance	The minimum absolute tolerance level that can be used for comparisons near zero.

Value Returned

t	n_val1 is nearly equal to n_val2.
nil	n_val1 is not equal to n_val2.

Examples

;; nearlyEqual check at 0.1% relative tolerance

relativeTolerance = 0.001

Val1 = 17.00

Val2 = 17.01

nearlyEqual(val1 val2 relativeTolerance) 
=> t

nearlyEqual(val2 val1 relativeTolerance) 
=> t

;; This is equivalent to:

abs(val1 – val2) < relativeTolerance * max(val1 val2)  
=> t

;; Other Examples

nearlyEqual(0.7777777777777 0.7777777777777777777777) 
=> t

nearlyEqual(0.7777777777777 0.7777777777777777777777 0.0) 
=> nil

nearlyEqual(nan nan) 
=> nil

nearlyEqual(infinity nan1) 
=> nil

Related Topics

eq

equal

eqv

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