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The Compleat User RPL Encyclopedia

(“Double Equals”)

obj obj    0 or 1
Keyboard Access:
  HP48S: [alpha] LS-1
         PRG TEST NXT
  HP48G: [alpha] LS-1
         PRG TEST
HP49/50: ALPHA  
         ENTRY   (press ENTRY once or twice to turn on the ALG annunciator)
         LS-PRG TEST
         «TESTS» NXT
Logical Equality Function: Tests if two objects are equal.

If the two (detagged) objects are of different types,  always returns 0, similar to . However, when the object types are the same, then  and  are not the same; for example:

    1 (true, because they are equal)
    0 (false, because they are not the same)
NOTE WELL: is NOT the same thing as is a test; is not.

The  function follows the “0 if false, 1 if true” rule. It is intended for use in program branching, but it can be used inside algebraic objects for “conditional calculations” without any program branching required.


    0 (false, because 5 ≠ 9)
    1 (true, because 5 = 5)
    0 (false, because 5 ≠ 2)
 returns A if C≠D, or A+B if C=D.
    same as above.
    same as above (because  automatically does ).
Examples of differences between HP48 and HP49/50:
HP48:         (’s to 1 if X exists)
HP49/50:      1 (even if X doesn’t exist or contains )

HP48:        1
HP49/50:     1 (no  is needed)

HP48       0 (Correct.)
HP49/50    1 (Wrong! They are in fact unequal, since matrix multiplication is not commutative.)
HP49G bug:     1 (should be )
This bug is not present in the HP49G+ or HP50G.

HP49/50 maximum integer input: no limit.

See also:

BYTES: 2.5