negative number raised to even power

[StephenG1CMZ]

(05-03-2015 04:47 PM)Dirk. Wrote:  Hi,
checking three "algebraic" calculators for the -2²-bug leads to interesing results:

CASIO CFX-9850GB PLUS:
There is no (+/-)-key but a special (-)-key to change sign. The algebraic (-)-sign of a number can be distinguished from the (-)-operation by a shorter symbol in front of the number.
*) 2(-)² -> Syn ERROR
*) -2² -> -4

SHARP EL-512S and SHARP EL-520V:
Both also have a special character so distingusih subtration from negarive numbers when pressing (+/-) to change sign.
*) 2(+/-)² -> -2² -> 4 at the EL-512
*) 2(+/-)² -> (-2)² -> 4 at the EL-520
*) (+/-)2² -> -2² -> 4
Pressing the (-)-key as the first key of a calculation leads to "0-" in the algebraic line of the display (on the prime it leads to "ANS-")
*) -2² -> 0-2² -> -4

-> On SHARP calculators it works like expected. The 520 even adds the brackets automatically to make this point even more clear.

Adding brackets to "explain" how a result is obtained seems an excellent idea.
Much clearer than expecting a user to see a difference between two minus signs - and knowing which is which and how to translate that onto a system having just one, in order to use a calculation.


I had thought I knew what -2^2 was, now I simply don't - and I would never have read -2^2 in C and thought EXOR rather than exponentiate.