My Desire calculator calculates incorrect

[Harry2]

Hi,

I search a better calculator for my Desire.

The stock calculator calculates incorrect,
e.g. 100-99.9=0.0999999999

The new calculator should very easy to use (and calculate correctly).
Mathematical functions to show graphically would be nice

With these many, many calculators in the market it is hard to find the right.

Harry

 

[Chilly McFreeze]

RealCalc is my favorite, because it looks (and functions) exactly like the scientific calculator I used at school!

 

[Szadzik]

I have always used Retro Calculator.

 

[Crumm]

Calculator by Stormin Dormin works good.

 

[Sloper59]

Strange. I just tried that calculation on my Desire HD and it gave the same result! What's happening there?

 

[JimSmith94]

Same result on my Sprint Evo!

 

[Harry2]

Thanks, the proposed calculators of yours calculates properly!

So it is a bug in the HTC calculator?

Harry

 

[KlaymenDK]

The stock calculator calculates incorrect, e.g. 100-99.9=0.0999999999

What's happening there?

This is most likely because the calculator isn't using enough internal precision (that is, the right type of variable for floating-point math; possibly a float where a double should have been used).

The thing is, computers love numbers but inherently suck at decimals.
You know how you can express "1/2" quite perfectly as "0.5", but for "1/3" you get the problem that "0.33333..." is never going to be entirely accurate? The same thing happens in binary, only on different occasions.

So when you hit one of those occasions, you will see a precision error in the form of a number that is "ever so slightly" smaller or larger than you'd expect.

Wikipedia: Representing_fractions_in_binary gives the following example.

Examples:
integer bits fractional bits

0.5    =