Determines whether two expressions are equal
(equal expr1 expr2 [fuzz])
The expression to be compared.
The expression to compare with expr1.
A real number defining the maximum amount by which expr1 and expr2 can differ and still be considered equal.
When comparing two real numbers (or two lists of real numbers, as in points), the two identical numbers can differ slightly if different methods are used to calculate them. You can specify a fuzz amount to compensate for the difference that may result from the different methods of calculation.
T if the two expressions are equal (evaluate to the same value); otherwise nil.
Given the following assignments:
(setq f1 '(a b c))
(setq f2 '(a b c))
(setq f3 f2)
(setq a 1.123456)
(setq b 1.123457)
f1 to f3:Compare
Command: (equal f1 f3)
f3 to f2:Compare
Command: (equal f3 f2)
a to b:Compare
Command: (equal a b)
a and b variables differ by .000001.The
a to b:, with fuzz argument of .000001:Compare
Command: (equal a b 0.000001)
a and b variables differ by an amount equal to the specified fuzz factor, so equal considers the variables equal.The
Comparing the eq and equal Functions
eq function finds that two lists or atoms are the same, the equal function also finds them to be the same.If the
equal function determines to be the same are also found equivalent by eq. However, two lists that equal determines to be the same may be found to be different according to the eq function.Any atoms that the
=(equal to)and eq functions.The