Seriously? Only 12 digits precision? o_O

[Stefan]

I just noticed that the numeric calculations in the Prime only have 12 digits precision.
I found that kind of disappointing and astonishing. For comparison: Even my 20€ calculator uses 14 digits precision. And the standard Android calculator app uses even more digits.
(And no, the "arbitrary" precision in CAS Mode is no help in these case where a floating point number is involved in the calculation.)

So why the heck doesn't the Prime use more digits? I understand that you have to cut of somewhere, but I would expect a couple of more digits from a calculator which is a magnitude higher in price than a simple school calculator.

[Joe Horn]

As you say, floating point number in Home have 12-BCD-digit mantissas, but did you know that floating point numbers in CAS (not the "arbitrary precision" integers) have 48-bit mantissas? That's roughly equivalent to 15 digits of decimal precision. So if you really need more than 12 digits (why???) then do your floating-point math in CAS, and you'll get more accuracy than your 14-digit calculator.

<opinion>The more expensive the calculator, the greater number of digits you should get? No. That's like saying the more expensive the camera, the more megapixels you should get. Not true at all. My Nikon with 12 sharp megapixels gets better results than my friend's camera with its 24 fuzzy megapixels. The number of pixels does not determine the quality of the camera. That's why some lower-megapixel cameras cost more than some cameras with more megapixels. Similarly, the number of digits does not determine the accuracy of the calculator. 12 reliable digits beats 15 unreliable digits. For example, I have a calculator that boasts having 24 internal digits, which it does... but most of its functions are only accurate to 12 digits, with the following 12 digits being garbage. 24 digits? I'm not impressed.</opinion>

[patrice]

What can you do with 14 digits that you can't with 12 ?
Counting US debt to the cent?

[Han]

(02-10-2014 07:46 PM)patrice Wrote:  What can you do with 14 digits that you can't with 12 ?
Counting US debt to the cent?

At the rate the US is handling its debt, I'm not sure 14 digits will be sufficient for very long. :-)

[CR Haeger]

(02-10-2014 07:46 PM)patrice Wrote:  What can you do with 14 digits that you can't with 12 ?
Counting US debt to the cent?

17.3E12 $US (and growing) is precise enough.

The Prime may not even be fast enough to count the $0.01 growth in real time. Check my math: ~$3.6 Billion growth/day = ~$42 Thousand/sec = ~4.2 "Mhz" in US pennies... Maybe the 400Mhz processor can keep up.

[Steve Simpkin]

(02-10-2014 08:05 PM)Han Wrote:  At the rate the US is handling its debt, I'm not sure 14 digits will be sufficient for very long. :-)

It a good thing we have arbitrary length integers in CAS then