Using Calculator, with input a real number between 0 and 1 for example, how do I get the angle for which the sin equals that real number?

That is, how do I enter arcsin (or any other arc-trig) to determine the angle? Thanks.

Bob

Here is what its is doing if calculate 13.5 / 1539 it shows me 8.7719e-03

While that is technically a correct answer I think I want tit to display it in the format I have become accustomed to like .0087719

What do I need to do to get it from this format 8.7719e-03 to this format .0087719

Right now I have OSX 10.4.11, Calculator version 4.0.6 but I have the same problem with Leopard too

David

Additional information

For an advanced discussion of why this happens, see “What Every Computer Scientist Should Know About Floating-Point Arithmetic”

Interesting though that the computer scientists at Apple do not know this, and that they even point out what they should know, but don’t, on their help site.

sin 360

(degree mode)

the answer should be zero but the calc shows -2.449293598294706e-16

os x 10.3.9

Sounds plausible, but that is setting the bar extremely low, don’t you think? I mean, the bar is pretty much just laying on the ground at that point.

I would think any calculator would use a number-storing format which could produce 100% accurate results on simple two-decimal arithmetic. When I think of rounding errors, I think more of legitimate repeating decimals like the square root of 2 or something.

And “precision” isn’t a misnomer at all.

Funny you should mention Netscape, because I actually thought of their frame sizing algorithm when I was thinking about this bug. I know it’s probably unrelated but it just reminded me of it. Basically, if you are using a frameset and you specify your frame dimensions in pixels, Netscape (at least up through version 4) would convert your pixels to a window size percentage, and then convert it back to pixels resulting in rounding errors all the time.

Kim and David,

Thanks for the Sun link. It looks like it explains floating points pretty thoroughly, but sheesh, 105 pages of engineer-speak. All I know is that even if this problem is legitimate, these errors should never make it to the consumer. As for our principal software engineer, I’m pretty sure his astonishment had more to do with not knowing how a calculator which had been around since 1984 could suddenly have this bug, as opposed to not knowing what floating point operations are. I mean, what could have possibly changed in Panther that would have introduced such a bug in the calculator? That is more the question…

Set the precision to 2.

I’m surprised this isn’t the default, as far more users can be expected to need to reconcile their check registers as opposed to needing numbers for structural load calculations or titration values.

c = a + b

or

c.setValue(a.add(b));

you’d probably select the first one.