Enum Expr 

pub enum Expr {
    Const(f64),
    Var(String),
    Add(Box<Expr>, Box<Expr>),
    Sub(Box<Expr>, Box<Expr>),
    Mul(Box<Expr>, Box<Expr>),
    Div(Box<Expr>, Box<Expr>),
    Pow(Box<Expr>, i32),
    Neg(Box<Expr>),
    Sqrt(Box<Expr>),
    Exp(Box<Expr>),
    Ln(Box<Expr>),
    Sin(Box<Expr>),
    Cos(Box<Expr>),
    Tan(Box<Expr>),
}

A symbolic expression over real constants and named variables.

Variants

Const(f64)

Var(String)

Add(Box<Expr>, Box<Expr>)

Sub(Box<Expr>, Box<Expr>)

Mul(Box<Expr>, Box<Expr>)

Div(Box<Expr>, Box<Expr>)

Pow(Box<Expr>, i32)

Integer power base^exp.

Neg(Box<Expr>)

Sqrt(Box<Expr>)

Principal square root.

Exp(Box<Expr>)

Natural exponential e^u.

Ln(Box<Expr>)

Natural logarithm ln(u) (domain u > 0).

Sin(Box<Expr>)

Cos(Box<Expr>)

Tan(Box<Expr>)

Tangent tan(u) (undefined where cos(u) = 0).

Implementations

impl Expr

pub fn eval(&self, env: &HashMap<String, f64>) -> Option<f64>

Numerically evaluate, given variable bindings. Returns None if a variable is unbound or a non-finite value is produced (e.g. division by zero, √negative).

Trait Implementations

impl Clone for Expr

fn clone(&self) -> Expr

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Expr

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Expr

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for Expr

fn eq(&self, other: &Expr) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Expr