KDE Kalk is also a calculator from the KDE project: https://github.com/KDE/kalk

I understand it is different from this project? I installed "kalk" from the AUR and was surprised get a UI ... maybe you are still on time to rename? I know this hurts, but its unfortunate that we have two tools with the same functional scope with the same name :/

This PR adds the gcd and lcm functions.

>> gcd(12, 18)
6
>> lcm(12, 18)
36

GCD is calculated with the modified Euclidean algorithm, and LCM is calculated with:

             ⎛           ⎞
             ⎜    ⎜a⎜     ⎟
lcm(a, b) =  ⎜ ───────── ⎟ × ⎜b⎜
             ⎜ gcd(a, b) ⎟
             ⎝           ⎠

I'm using the windows binary an what I'm missing the most ATM is a way to define constants I use often so I don't have to define them as variables every session. I suppose it would mean having at least an external config file... which I would prefer to be human-readable/editable, maybe some json?

Patching of Cargo.toml is no longer needed. The relevant commit on gmp-mpfr-sys has been merged and is part of the 1.4.8 release. I've removed the patch locally and regenerated Cargo.lock but for some reason I'm not able to push the changes and create a PR. It seems like some more changes (nix flakes?) are needed to address conflicts flagged by git when pushing, hence my request here.

Thanks!

For example could be written as

f(x) = {-x-x if x≤-3; x+3 if -3≤x≤0; 3-2x if 0≤x≤3; 0.5x-4.5 if 3≤x}

or:

f(x) = {x≤-3: -x-x; -3≤x≤0: x+3; 0≤x≤3: 3-2x; 3≤x: 0.5x-4.5}

Running cargo install kalk_cli is failing for me with:

  Updating crates.io index
  Downloaded kalk_cli v0.1.10
  Downloaded 1 crates (8.4 KB) in 0.94s
  Installing kalk_cli v0.1.10
error: failed to compile `kalk_cli v0.1.10`, intermediate artifacts can be found at `/tmp/cargo-installrPOC9T`

Caused by:
  failed to parse lock file at: /home/ewpratten/.cargo/registry/src/github.com-1ecc6299db9ec823/kalk_cli-0.1.10/Cargo.lock

Caused by:
  invalid serialized PackageId for key `package.dependencies`

cargo -V is outputting:

cargo 1.35.0 (6f3e9c367 2019-04-04)

Exponentiation does not seem to work in the web interface (Firefox).

As the web interface immediately converts the input into special symbols it is not possible to do inputs such as 2**3 as these get immediately turned into 2⋅⋅3, which then results in Unexpected token: 'Star'

Also I am not able to input ^2 for some reason as the circumflex gets immediately deleted.

The console version works fine.

An Iverson Bracket is simply a predicate in square brackets which evaluates to 0 if false or 1 if true. It is great for defining functions in multiple pieces, for example f(x)=x[x<0]+x^2[x>0]:

Currently when I run kalk help (out of habit) I get a weird error of Undefined variable: 'h'.. I think switching to a ready solution would greatly benefit future development.

Something like Clap requires minimal setup while providing a lot of great features (like generating shell completions which are hard to maintain by hand). This will add to compile time though so it is worth thinking about it.

I am willing to help with the transition.

Forgive me if I am missing it, but it seems like we do not have support permutations and combinations calculation, correct? Can someone confirm this?

I realized this as I was using kalker in my school test. :)

$ f(x) =  x^2
$ f 2
4
$ g(x,y) = x^2y
g 1 2
Expected 2 arguments for function g, but got 1.

Haskell-like function application would be very useful, is it meant to be supported only for one-param functions?

It would be really nice if kalker was available through F-Droid. As far as I know, kalker fulfills almost all criteria to be accepted by F-Droid, except some structural requirement of having Metadata about the project in a certain location. It would be amazing if you could propose adding it.

I would like to define custom built in functions from Rust call-backs. This makes the functions more extendable as you have access to Rust's functionality like println! along with other Rust math libraries. Is this currently possible? If not I think this should be considered. It allows fore greater extendibility without the need of another parser.

I would like to retrieve all user defined variables from a Context but this doesn't seem like it's currently possible. Being able to delete them would be useful too.

When using eval to parse variable's to the power only positive values are considered.

use kalk::parser;

fn main() {
    let mut parser_context = parser::Context::new();
    let result = parser::eval(&mut parser_context, &"x^2=4")
        .unwrap()
        .unwrap();

    println!("{}", result);
}

Outputs:

2

This is missing the solution x=-2.

When I want to calculate sin(90deg) without brackets this is what I got:

>> sin 90deg
0.0156031853 rad

which is actually:

>> (sin 90)deg
0.0156031853 rad

Maybe the "deg" can have a higher order in calculation?

By the way, If the function is provided with "degrees"

>> sin (90deg)
1 rad

the "rad" after "sin" "cos" "tan" still exists. But these functions should "eat" the "rad".