qfall-math 0.1.1

// Copyright © 2023 Marvin Beckmann
//
// This file is part of qFALL-math.
//
// qFALL-math is free software: you can redistribute it and/or modify it under
// the terms of the Mozilla Public License Version 2.0 as published by the
// Mozilla Foundation. See <https://mozilla.org/en-US/MPL/2.0/>.

//! Implementations to evaluate a [`PolyOverQ`].
//! For each reasonable type, an implementation
//! of the [`Evaluate`] trait should be implemented.

use super::PolyOverQ;
use crate::{rational::Q, traits::Evaluate};
use flint_sys::fmpq_poly::fmpq_poly_evaluate_fmpq;

impl<Rational: Into<Q>> Evaluate<Rational, Q> for PolyOverQ {
    /// Evaluates a [`PolyOverQ`] on a given input.
    ///
    /// Parameters:
    /// - `value`: the value with which to evaluate the polynomial.
    ///
    /// Returns the evaluation of the polynomial as a [`Q`].
    ///
    /// # Examples
    /// ```
    /// use qfall_math::traits::*;
    /// use qfall_math::rational::Q;
    /// use qfall_math::rational::PolyOverQ;
    /// use std::str::FromStr;
    ///
    /// let poly = PolyOverQ::from_str("5  0 1 2/3 -3/2 1").unwrap();
    /// let value = Q::from((3, 2));
    /// let res = poly.evaluate(&value);
    /// ```
    fn evaluate(&self, value: Rational) -> Q {
        let value = value.into();
        let mut res = Q::default();

        unsafe { fmpq_poly_evaluate_fmpq(&mut res.value, &self.poly, &value.value) };

        res
    }
}

#[cfg(test)]
mod test_evaluate {
    use crate::rational::{PolyOverQ, Q};
    use crate::traits::Evaluate;
    use std::str::FromStr;

    /// Tests if evaluate works for [`Q`] as input
    #[test]
    fn eval_q_working() {
        let poly = PolyOverQ::from_str("2  1 2/7").unwrap();

        let res = poly.evaluate(Q::from((7, 3)));

        assert_eq!(Q::from((5, 3)), res);
    }

    /// Tests if evaluate works with negative values
    #[test]
    fn eval_q_negative() {
        let poly = PolyOverQ::from_str("2  1 2/7").unwrap();

        let res = poly.evaluate(Q::from((-7, 3)));

        assert_eq!(Q::from((1, 3)), res);
    }

    /// Tests if evaluate works with large rationals
    #[test]
    fn eval_q_large() {
        let q_str = format!("{}/{}", u64::MAX, i64::MIN);
        let q_str_rev = format!("{}/{}", i64::MIN, u64::MAX);
        let large_string = format!("2  0 {q_str}");
        let poly = PolyOverQ::from_str(&large_string).unwrap();

        let res = poly.evaluate(Q::from_str(&q_str_rev).unwrap());

        assert_eq!(Q::ONE, res);
    }
}

#[cfg(test)]
mod test_evaluate_z {
    use crate::integer::Z;
    use crate::rational::{PolyOverQ, Q};
    use crate::traits::Evaluate;
    use std::str::FromStr;

    /// Tests if evaluate works for [`Z`] as input
    #[test]
    fn eval_z_working() {
        let poly = PolyOverQ::from_str("2  1 2/7").unwrap();

        let res = poly.evaluate(Z::from(3));

        assert_eq!(Q::from((13, 7)), res);
    }

    /// Tests if evaluate works with negative values
    #[test]
    fn eval_z_negative() {
        let poly = PolyOverQ::from_str("2  1 2/7").unwrap();

        let res = poly.evaluate(&Z::from(-5));

        assert_eq!(Q::from((-3, 7)), res);
    }

    /// Test if evaluate works with large nominators and denominators
    #[test]
    fn eval_large_nom_denom_large_ref_z() {
        let q_str = format!("{}/{}", u64::MAX, i64::MIN);
        let large_string = format!("2  -{} {q_str}", u64::MAX);
        let poly = PolyOverQ::from_str(&large_string).unwrap();

        let res = poly.evaluate(&Z::from(i64::MIN));

        assert_eq!(Q::default(), res);
    }

    /// Test if evaluate works with max of [`i64`],[`i32`], ...
    #[test]
    fn eval_max() {
        let poly = PolyOverQ::from_str("2  1/7 2/3").unwrap();

        // signed
        let _ = poly.evaluate(i64::MAX);
        let _ = poly.evaluate(i32::MAX);
        let _ = poly.evaluate(i16::MAX);
        let _ = poly.evaluate(i8::MAX);

        //unsigned
        let _ = poly.evaluate(u64::MAX);
        let _ = poly.evaluate(u32::MAX);
        let _ = poly.evaluate(u16::MAX);
        let _ = poly.evaluate(u8::MAX);
    }

    /// Test if evaluate works with min of [`i64`],[`i32`], ...
    #[test]
    fn eval_min() {
        let poly = PolyOverQ::from_str("2  1/7 2/3").unwrap();

        // signed
        let _ = poly.evaluate(i64::MIN);
        let _ = poly.evaluate(i32::MIN);
        let _ = poly.evaluate(i16::MIN);
        let _ = poly.evaluate(i8::MIN);

        // unsigned
        let _ = poly.evaluate(u64::MIN);
        let _ = poly.evaluate(u32::MIN);
        let _ = poly.evaluate(u16::MIN);
        let _ = poly.evaluate(u8::MIN);
    }
}

#[cfg(test)]
mod test_evaluate_q {
    use crate::{
        rational::{PolyOverQ, Q},
        traits::Evaluate,
    };
    use std::str::FromStr;

    /// Tests if evaluate works for [`Q`] as input
    #[test]
    fn eval_q_working() {
        let poly = PolyOverQ::from_str("2  1 2/7").unwrap();

        let res = poly.evaluate(&Q::from((7, 3)));

        assert_eq!(Q::from((5, 3)), res);
    }

    /// Tests if evaluate works with negative values
    #[test]
    fn eval_q_negative() {
        let poly = PolyOverQ::from_str("2  1 2/7").unwrap();

        let res = poly.evaluate(&Q::from((-7, 3)));

        assert_eq!(Q::from((1, 3)), res);
    }

    /// Tests if evaluate works with large rationals
    #[test]
    fn eval_q_large() {
        let q_str = format!("{}/{}", u64::MAX, i64::MIN);
        let q_str_rev = format!("{}/{}", i64::MIN, u64::MAX);
        let large_string = format!("2  0 {q_str}");
        let poly = PolyOverQ::from_str(&large_string).unwrap();

        let res = poly.evaluate(&Q::from_str(&q_str_rev).unwrap());

        assert_eq!(Q::ONE, res);
    }
}