PEMDAS issues

[adnan360]

First of all thanks for implementing PEMDAS. 🏆 It was great to see you implement it that fast.

I did some testing:

$ ./bcalc '(2+2)*2'
2
$ ./bcalc '2*(2+2)'
26
$ ./bcalc '2^(2+2)'
26
$ ./bcalc '(2+2)^2'
3
$ ./bcalc '(2)^2'
1
$ ./bcalc '2+2+2^2'
8

All of these are wrong. Am I doing anything wrong?

[adnan360]

I've tried with adding [...] to the numbers and the results were correct. But readme says "[] = denotes a multi-digit number". 2 is not multi-digit, so it should not require square brackets if I understand correcly.

[Phate6660]

Hm, this is probably an issue with the parser.
Oh wait, actually think I see why.
It'll have to wait though, I have to be away from PC for a while.

[adnan360]

No problem. Good things take time. :)

But I'd be happy if I didn't have to put in all the [] for multidigit numbers too in the future. It takes time to type them for each number.

[Phate6660]

Oh don't worry, that'll only be temorary.
I'm working on just allowing multi-digit characters like normal, I just forgot to stick it in the readme.

[adnan360]

That'd be great. Take your time though. No hurry from my side.

[Phate6660]

Hey, I just wanted to let you know that I've started to work on it.
I re-wrote a bit of the parser.
It's fairly error prone (which is why it's a WIP on a separate branch), but you can at least now use multiple-digit numbers without specifying them with [].
You can track the progress here: https://github.com/Phate6660/bcalc/tree/multi-digit-and-parser

[Phate6660]

I believe I got it working!
I just need to tidy up the script a bit, add some finishing touches to the README.
Then I'll push it the branch.
When I do, would you mind testing it again? Before I merge it into master.

[Phate6660]

It's pushed!

[Phate6660]

I just realized I forgot to actually explain what I did.
I believe now I got it to actually support PEMDAS, I tested it myself.
And [] is now no longer needed. You can you multiple-digit numbers just like normal now.

[Phate6660]

I actually feel pretty confident about this. All of the calculations I've tried have worked.
Obviously I'm not going to try every combination, so there's bound to be more bugs.
But I feel like this is a stable and working enough base to merge.
I'm going to keep this issue open, feel free report anything you find here! :)

[adnan360]

WOW. Thanks for implementing it that fast.

With my initial checks it seems to be working fine. I think it's ready to be included in my config. I'll close it if I find no more issues.

[adnan360]

I think I found some issues with exponents:

$ ./bcalc '(2^2)*2'
0
$ ./bcalc '(2^2)*1'
0
$ ./bcalc '9^(1/2)'
1

Tested on master

[Phate6660]

./bcalc '9^(1/2)' actually isn't wrong.

1/2 = 0
If you want the remainder, you need to use %.
1%2 = 1

9^0 = 0
9^1 = 9

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I'll have to look into the other ones though.

[Phate6660]

That is my bad though, I forgot to document that % is a valid math operation.

[Phate6660]

I fixed the other two.
The problem was that I forgot to convert ^ to ** while calculating things in parentheses.
As ** is what bash uses for exponents.

[adnan360]

./bcalc '9^(1/2)' actually isn't wrong.

Well, I have been taught in school that having an exponent of 1/2(=0.5) is like having a sqroot. I've run this through multiple online calculators and they all seem to output 3. (1) (2)

But this is in a way my fault too. 1/2 returns decimal, so it should not work anyway until decimals are implemented. So I wouldn't be worried about it too much now. But a message would be nice when decimals/fractions like this occur.

[adnan360]

I fixed the other two.
The problem was that I forgot to convert ^ to ** while calculating things in parentheses.
As ** is what bash uses for exponents.

Yeah, thanks. Tested with some basic inputs and seems to be working fine now.

[adnan360]

I think I got another issue:

$ ./bcalc '((2+2)+2)'
4
$ ./bcalc '(((2+2)+2)+2)'
224

Answer should be 6 and 8

[Phate6660]

Yeah, I can already see why. The parser was not built with nested parenthesis in mind.
I'll definitely need to re-work the parser to account for that. Or at least the parenthesis part anyway.

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Sorry for the late reply, I'm away from PC. Spending some time with the family right now.
I just had a little time to comment because we're taking a slight break to make food.

[adnan360]

No problem. Take your time.