minicas 0.0.1

A smol Computer Algebra System.

Creating an AST is easiest done by parsing it from a string:

use minicas_core::ast::*;
let mut n = Node::try_from("5x * 2x").unwrap();

Though an AST may be constructed manually (see [minicas_core] tests for examples of this).

Once you have an AST, you can typically work with it by calling methods on it, such as finite_eval():

# use minicas_core::ast::*;
// EG: Evaluating an expression with variables
assert_eq!(
    Node::try_from("{x if x > y; otherwise y}")
        .unwrap()
        .finite_eval(&vec![("x", 42.into()), ("y", 4.into())]),
    Ok(42.into()),
);

// EG: Interval arithmetic
assert_eq!(
    Node::try_from("x - 2y")
        .unwrap()
        .eval_interval(&vec![
            ("x", (1.into(), 2.into())),
            ("y", (5.into(), 6.into()))
        ])
        .unwrap()
        .collect::<Result<Vec<_>, _>>(),
    Ok(vec![((-11).into(), (-8).into())]),
);

Theres also a number of algorithm modules in [core::ast]:

# use minicas::prelude::*;
use minicas::algs::*;

// EG: Rearrange the equation
let mut lhs = NodeInner::new_var("d");
make_subject(
    &mut lhs,
    &Node::try_from("sqrt(pow(x2 - x1, 2) + pow(y2 - y1, 2))").unwrap(),
    &Node::try_from("x2").unwrap() // rearrange for x2
);
assert_eq!(
    &lhs,
    Node::try_from("0 ± sqrt(pow(d, 2) - pow(y2 - y1, 2)) + x1")
        .unwrap()
        .as_inner(),
);

// EG: Constant folding
let mut n = Node::try_from("x + (3 * --2)").unwrap();
assert_eq!(fold(&mut n), Ok(()),);
assert_eq!(n, Node::try_from("x + 6").unwrap());