• ← Min
• → TrueQ

SameQ (===)

WMA link

SameQ[x, y]

x === y

returns True if x and y are structurally identical. Commutative properties apply, so if x === y then y === x.

• SameQ requires exact correspondence between expressions, expect that it still considers Real numbers equal if they differ in their last binary digit.
  
• $e_1$ === $e_2$ === $e_3$ gives True if all the ei's are identical.
  
• SameQ[] and SameQ[expr] always yield True.

Any object is the same as itself:

• • a === a

Degenerate cases of SameQ showing off how you can chain ===:

• • SameQ[a] === SameQ[] === True

Unlike Equal, SameQ only yields True if x and y have the same type:

• • {1==1., 1===1.}

• • 2./9. === .2222222222222222`15.9546

The comparison consider just the lowest precision

• • .2222222`6 === .2222`3

Notice the extra decimal in the rhs. Because the internal representation,
$0.222`3$ is not equivalent to $0.2222`3$:

• • .2222222`6 === .222`3

15.9546 is the value of $MaxPrecision