ihateintegrals 0.1.2

A computer algebra library for solving integrals.
Documentation 
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use std::rc::Rc;

use crate::{
    argument::Argument,
    convenience_expressions::sum_of_iter,
    expressions::{Derivative, Expression},
};

use super::DerivationRule;

pub struct DerivativeOfSum {}

impl DerivationRule for DerivativeOfSum {
    fn apply(&self, input: Expression) -> Vec<(Expression, Rc<Argument>)> {
        let derivative = match input {
            Expression::Derivative(ref d) => d,
            _ => return vec![],
        };

        let Expression::Sum(ref s) = derivative.exp() else {
            return vec![];
        };

        vec![(
            sum_of_iter(
                &mut s
                    .terms()
                    .iter()
                    .map(|term| Derivative::of(term.clone(), derivative.relative_to())),
            ),
            Argument::new(
                String::from("Split derivative over addition"),
                vec![input],
                self.name(),
            ),
        )]
    }
    fn name(&self) -> String {
        String::from("DerivativeOfSum")
    }
}

#[cfg(test)]
mod tests {
    use crate::{convenience_expressions::v, expressions::sum::sum_of};

    use super::*;

    #[test]
    fn test_1() {
        let rule = DerivativeOfSum {};

        let start = Derivative::of(sum_of(&[v("a"), v("b")]), v("c"));
        let result = rule.apply(start).first().unwrap().0.clone();

        assert_eq!(
            result,
            sum_of(&[
                Derivative::of(v("a"), v("c")),
                Derivative::of(v("b"), v("c"))
            ])
        )
    }
}