Crate parametrizer

A simple, safe crate for parsing properly-formatted math strings which represent parametric functions into Rust functions that compute them. Ported from an earlier version for Javascript.

Example Usage

Simply create a Parametrizer struct by passing a string to one of its constructors and call the evaluate method:

use crate::parametrizer::Parametrizer;

let division = Parametrizer::new("4\\2").unwrap();
let subtraction = Parametrizer::new("15-3*t").unwrap();
let spaces = Parametrizer::new("6 + T").unwrap();
let sin = Parametrizer::new("sin(t*t + t - 1)").unwrap();

assert_eq!(2, division.evaluate(8));
assert_eq!(6, subtraction.evaluate(3));
assert_eq!(8, spaces.evaluate(2));
assert_eq!(11.0_f64.sin(), sin.evaluate(3.0));

use crate::parametrizer::Parametrizer;

let constant = Parametrizer::new("1.35").unwrap();

assert_eq!(1.35, constant.evaluate(2.0));
assert_eq!(1.35, constant.evaluate(3.4));

use crate::parametrizer::Parametrizer;

let variable = Parametrizer::new("t").unwrap();

assert_eq!(3.0, variable.evaluate(3.0));
assert_ne!(4.2, variable.evaluate(1.25));

use crate::parametrizer::Parametrizer;

let addition = Parametrizer::new("1+t").unwrap();

assert_eq!(9.0, addition.evaluate(8.0));
assert_eq!(1.16, addition.evaluate(0.16));

use crate::parametrizer::Parametrizer;

let equation = Parametrizer::new("13+((2*t)+5)").unwrap();

assert_eq!(20, equation.evaluate(1));
assert_eq!(30, equation.evaluate(6));

use crate::parametrizer::Parametrizer;

let division = Parametrizer::new("6/t").unwrap();

assert_eq!(2, division.evaluate(3));
assert_eq!(3, division.evaluate(2));

use crate::parametrizer::Parametrizer;

let equation = Parametrizer::new("13-t").unwrap();
let negation = Parametrizer::new("-t").unwrap();

assert_eq!(10, equation.evaluate(3));
assert_eq!(-9, negation.evaluate(9));

use crate::parametrizer::Parametrizer;

let dynamic_rand = Parametrizer::new("rd(2+t<4*t)").unwrap();
let computed_rand = Parametrizer::new("rc(4<8)").unwrap();

assert_eq!(computed_rand.evaluate(2), computed_rand.evaluate(4));
assert!(4 <= dynamic_rand.evaluate(2));
assert!(16 > dynamic_rand.evaluate(4));

use crate::parametrizer::Parametrizer;

//Piecewise functions
let p1 = Parametrizer::new("p2>0|4>2|8>6").unwrap();
let p2 = Parametrizer::new("p2*t>0|4>2").unwrap();

//Looping piecewise functions
let p3 = Parametrizer::new("p[10]18>0|23>4").unwrap();

assert_eq!(2, p1.evaluate(1));
assert_eq!(4, p1.evaluate(5));
assert_eq!(2, p2.evaluate(1));
assert_eq!(4, p2.evaluate(9));

assert_eq!(18, p3.evaluate(23));
assert_eq!(23, p3.evaluate(106));

The underlying terms are public to allow for the manual composition of terms in code to avoid the string parsing overhead. See the term module documentation for more information. See the Parametrizer struct’s implementation documentation to see more usage examples.

Modules

term

Structs

Parametrizer	Main struct for parametrizing strings. Contains a pointer to the top-level term, which will contain pointers to lower leves for recursive evaluations
ParametrizerError	An error which describes why parametrization failed. Contains the param string which failed as well as the reason for failure.
ParametrizerFunction	A pair containing a function on 64-bit float numbers and a shorthand associated with it.

Traits

Number