numopt 0.2.1

Numerical optimization problem abstractions, solver interfaces, and modeling tools.
Documentation 
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//! Sine function.

use std::fmt;
use std::rc::Rc;
use std::collections::HashMap;

use crate::model::node::Node;
use crate::model::node_base::NodeBase;
use crate::model::node_std::{NodeStd, NodeStdProp};
use crate::model::node_func::NodeFunc;
use crate::model::constant::ConstantScalar;

/// Sine function.
pub struct FunctionSin {
    arg: Node
}

impl FunctionSin {

    /// Creates new sine expression node.
    pub fn new(arg: Node) -> Node {
        Node::FunctionSin(Rc::new(
            Self {
                arg: arg,
            }
        ))
    }
}

impl NodeBase for FunctionSin {

    fn arguments(&self) -> Vec<&Node> {
        vec![&self.arg]
    }

    fn partial(&self, arg: &Node) -> Node { 
        if self.arg == *arg {
            return self.arg.cos();
        }
        else {
            return ConstantScalar::new(0.);
        }
    }

    fn evaluate(&self, var_values: &HashMap<&Node, f64>) -> f64 {
        self.arg.evaluate(var_values).sin()
    }
}

impl NodeStd for FunctionSin {

    fn std_properties(&self) -> NodeStdProp {
        let mut p = self.arg.std_properties();
        p.affine = false;
        p
    }
}

impl<'a> fmt::Display for FunctionSin {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "sin({})", self.arg)
    }
}

#[cfg(test)]
mod tests {

    use super::*;
    use crate::model::node_base::NodeBase;
    use crate::model::node_diff::NodeDiff;
    use crate::model::variable::VariableScalar;

    #[test]
    fn sin_partial() {

        let x = VariableScalar::new_continuous("x");
        let y = VariableScalar::new_continuous("x");

        let z = x.cos();
        
        let z1 = z.partial(&x);
        assert_eq!(format!("{}", z1), "-1*sin(x)");
        
        let z2 = z.partial(&y);
        assert!(z2.is_constant_with_value(0.));
    }

    #[test]
    fn sin_derivative() {

        let x = VariableScalar::new_continuous("x");
        let y = VariableScalar::new_continuous("y");

        let z1 = x.sin();
        let z1x = z1.derivative(&x);
        let z1y = z1.derivative(&y);
        assert_eq!(format!("{}", z1x), "cos(x)");
        assert!(z1y.is_constant_with_value(0.));

        let z2 = (5.*&x + 3.*&y).sin();
        let z2x = z2.derivative(&x);
        let z2y = z2.derivative(&y);
        assert_eq!(format!("{}", z2x), "cos(5*x + 3*y)*5");
        assert_eq!(format!("{}", z2y), "cos(5*x + 3*y)*3");
    }

    #[test]
    fn sin_std_properties() {

        let x = VariableScalar::new_continuous("x");
        let y = VariableScalar::new_continuous("y");

        let z1 = &x.sin();
        let p1 = z1.std_properties();
        assert!(!p1.affine);
        assert_eq!(p1.a.len(), 1);
        assert!(p1.a.contains_key(&x));

        let z2 = 3.*(&x + &y).sin();
        let p2 = z2.std_properties();
        assert!(!p2.affine);
        assert_eq!(p2.a.len(), 2);
        assert!(p2.a.contains_key(&x));
        assert!(p2.a.contains_key(&y));
    }
}