Posts: 312

Threads: 25

Joined: Jan 1970

Don:

This "bug" is present in the oldest HP calculators. I suppose it's due to the fact that powers were calculated by way of logarithms, and you can't apply the LN function to a negative number. More modern calculators circumvent this problem by analyzing both numbers, and work the sign of the result based on that. If I'm not mistaken, the HP-67/97 were the first calculators to be able to raise negative numbers to whole powers.

By the same token, the oldest machines allowed you to CHS the number zero, and I think I read somewhere that the HP-35 gave an error message if you tried to calculate the square root of -0. More modern calculators don't change the sign of zero no matter how many times you press CHS.

Ain't life innerestin'?

-Ernie

Posts: 1,193

Threads: 43

Joined: Jul 2005

Certinly y^x was calculated using logarythms, and negative base was not allowed. I think it was around the HP67 time when the internal routines were improved to accept integer powers for negative bases. It was a nice improvement but not more than a sophistication handled before (with no complaints) by the users ...

Posts: 52

Threads: 11

Joined: Jan 1970

Just checked it.

Regards,

Harry