317: Feature/complex from str r=cuviper

This commit adds a basic parser for Complex types in Cartesian form, per https://github.com/rust-num/num/issues/289. It will take numbers of the form `a + bi`, `ai + b`, `a - bi`, `ai - b`, `a`, or `ai`. At least one space between the real/imaginary parts and the operator is mandatory; without bringing in a dependency on some regex crate, it's nontrivial to handle cases like, e.g., 0.217828e+1+31.4159E-1, or a similar case with polar coordinates. I could work on these issues later if you like.
This commit is contained in:
bors[bot] 2017-07-19 22:19:24 +00:00
commit a8ebac5af1
1 changed files with 233 additions and 18 deletions

View File

@ -22,10 +22,12 @@ extern crate rustc_serialize;
#[cfg(feature = "serde")]
extern crate serde;
use std::error::Error;
use std::fmt;
#[cfg(test)]
use std::hash;
use std::ops::{Add, Div, Mul, Neg, Sub};
use std::str::FromStr;
use traits::{Zero, One, Num, Float};
@ -178,7 +180,7 @@ impl<T: Clone + Float> Complex<T> {
let (r, theta) = self.to_polar();
Complex::from_polar(&(r.sqrt()), &(theta/two))
}
/// Raises `self` to a floating point power.
#[inline]
pub fn powf(&self, exp: T) -> Complex<T> {
@ -187,25 +189,25 @@ impl<T: Clone + Float> Complex<T> {
let (r, theta) = self.to_polar();
Complex::from_polar(&r.powf(exp), &(theta*exp))
}
/// Returns the logarithm of `self` with respect to an arbitrary base.
#[inline]
pub fn log(&self, base: T) -> Complex<T> {
// formula: log_y(x) = log_y(ρ e^(i θ))
// = log_y(ρ) + log_y(e^(i θ)) = log_y(ρ) + ln(e^(i θ)) / ln(y)
// = log_y(ρ) + i θ / ln(y)
// formula: log_y(x) = log_y(ρ e^(i θ))
// = log_y(ρ) + log_y(e^(i θ)) = log_y(ρ) + ln(e^(i θ)) / ln(y)
// = log_y(ρ) + i θ / ln(y)
let (r, theta) = self.to_polar();
Complex::new(r.log(base), theta / base.ln())
}
/// Raises `self` to a complex power.
#[inline]
pub fn powc(&self, exp: Complex<T>) -> Complex<T> {
// formula: x^y = (a + i b)^(c + i d)
// = (ρ e^(i θ))^c (ρ e^(i θ))^(i d)
// = (ρ e^(i θ))^c (ρ e^(i θ))^(i d)
// where ρ=|x| and θ=arg(x)
// = ρ^c e^(d θ) e^(i c θ) ρ^(i d)
// = p^c e^(d θ) (cos(c θ)
// = p^c e^(d θ) (cos(c θ)
// + i sin(c θ)) (cos(d ln(ρ)) + i sin(d ln(ρ)))
// = p^c e^(d θ) (
// cos(c θ) cos(d ln(ρ)) sin(c θ) sin(d ln(ρ))
@ -214,14 +216,14 @@ impl<T: Clone + Float> Complex<T> {
// = from_polar(p^c e^(d θ), c θ + d ln(ρ))
let (r, theta) = self.to_polar();
Complex::from_polar(
&(r.powf(exp.re) * (-exp.im * theta).exp()),
&(r.powf(exp.re) * (-exp.im * theta).exp()),
&(exp.re * theta + exp.im * r.ln()))
}
/// Raises a floating point number to the complex power `self`.
#[inline]
pub fn expf(&self, base: T) -> Complex<T> {
// formula: x^(a+bi) = x^a x^bi = x^a e^(b ln(x) i)
// formula: x^(a+bi) = x^a x^bi = x^a e^(b ln(x) i)
// = from_polar(x^a, b ln(x))
Complex::from_polar(&base.powf(self.re), &(self.im * base.ln()))
}
@ -877,6 +879,97 @@ impl<T> fmt::Binary for Complex<T> where
}
}
impl<T> FromStr for Complex<T> where
T: FromStr + Num + Clone
{
type Err = ParseComplexError<T::Err>;
/// Parses `a +/- bi`; `ai +/- b`; `a`; or `bi` where `a` and `b` are of type `T`
fn from_str(s: &str) -> Result<Self, Self::Err>
{
let imag = match s.rfind('j') {
None => 'i',
_ => 'j'
};
let mut b = String::with_capacity(s.len());
let mut first = true;
let char_indices = s.char_indices();
let mut pc = ' ';
let mut split_index = s.len();
for (i, cc) in char_indices {
if cc == '+' && pc != 'e' && pc != 'E' && i > 0 {
// ignore '+' if part of an exponent
if first {
split_index = i;
first = false;
}
// don't carry '+' over into b
pc = ' ';
continue;
} else if cc == '-' && pc != 'e' && pc != 'E' && i > 0 {
// ignore '-' if part of an exponent or begins the string
if first {
split_index = i;
first = false;
}
// DO carry '-' over into b
}
if pc == '-' && cc == ' ' && !first {
// ignore whitespace between minus sign and next number
continue;
}
if !first {
b.push(cc);
}
pc = cc;
}
// split off real and imaginary parts, trim whitespace
let (a, _) = s.split_at(split_index);
let a = a.trim_right();
let mut b = b.trim_left();
// input was either pure real or pure imaginary
if b.is_empty() {
b = match a.ends_with(imag) {
false => "0i",
true => "0"
};
}
let re;
let im;
if a.ends_with(imag) {
im = a; re = b;
} else if b.ends_with(imag) {
re = a; im = b;
} else {
return Err(ParseComplexError::new());
}
// parse re
let re = try!(T::from_str(re).map_err(ParseComplexError::from_error));
// pop imaginary unit off
let mut im = &im[..im.len()-1];
// handle im == "i" or im == "-i"
if im.is_empty() || im == "+" {
im = "1";
} else if im == "-" {
im = "-1";
}
// parse im
let im = try!(T::from_str(im).map_err(ParseComplexError::from_error));
Ok(Complex::new(re, im))
}
}
#[cfg(feature = "serde")]
impl<T> serde::Serialize for Complex<T>
where T: serde::Serialize
@ -900,6 +993,51 @@ impl<T> serde::Deserialize for Complex<T> where
}
}
#[derive(Debug, PartialEq)]
pub struct ParseComplexError<E>
{
kind: ComplexErrorKind<E>,
}
#[derive(Debug, PartialEq)]
enum ComplexErrorKind<E>
{
ParseError(E),
ExprError
}
impl<E> ParseComplexError<E>
{
fn new() -> Self {
ParseComplexError {
kind: ComplexErrorKind::ExprError,
}
}
fn from_error(error: E) -> Self {
ParseComplexError {
kind: ComplexErrorKind::ParseError(error),
}
}
}
impl<E: Error> Error for ParseComplexError<E>
{
fn description(&self) -> &str {
match self.kind {
ComplexErrorKind::ParseError(ref e) => e.description(),
ComplexErrorKind::ExprError => "invalid or unsupported complex expression"
}
}
}
impl<E: Error> fmt::Display for ParseComplexError<E>
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.description().fmt(f)
}
}
#[cfg(test)]
fn hash<T: hash::Hash>(x: &T) -> u64 {
use std::hash::{BuildHasher, Hasher};
@ -915,6 +1053,7 @@ mod test {
use super::{Complex64, Complex};
use std::f64;
use std::str::FromStr;
use traits::{Zero, One, Float};
@ -1018,7 +1157,7 @@ mod test {
fn close(a: Complex64, b: Complex64) -> bool {
close_to_tol(a, b, 1e-10)
}
fn close_to_tol(a: Complex64, b: Complex64, tol: f64) -> bool {
// returns true if a and b are reasonably close
(a == b) || (a-b).norm() < tol
@ -1052,7 +1191,7 @@ mod test {
assert!(-f64::consts::PI <= c.ln().arg() && c.ln().arg() <= f64::consts::PI);
}
}
#[test]
fn test_powc()
{
@ -1063,7 +1202,7 @@ mod test {
let c = Complex::new(1.0 / 3.0, 0.1);
assert!(close_to_tol(a.powc(c), Complex::new(1.65826, -0.33502), 1e-5));
}
#[test]
fn test_powf()
{
@ -1071,7 +1210,7 @@ mod test {
let r = c.powf(3.5);
assert!(close_to_tol(r, Complex::new(-0.8684746, -16.695934), 1e-5));
}
#[test]
fn test_log()
{
@ -1079,18 +1218,18 @@ mod test {
let r = c.log(10.0);
assert!(close_to_tol(r, Complex::new(0.349485, -0.20135958), 1e-5));
}
#[test]
fn test_some_expf_cases()
{
let c = Complex::new(2.0, -1.0);
let r = c.expf(10.0);
assert!(close_to_tol(r, Complex::new(-66.82015, -74.39803), 1e-5));
let c = Complex::new(5.0, -2.0);
let r = c.expf(3.4);
assert!(close_to_tol(r, Complex::new(-349.25, -290.63), 1e-2));
let c = Complex::new(-1.5, 2.0 / 3.0);
let r = c.expf(1.0 / 3.0);
assert!(close_to_tol(r, Complex::new(3.8637, -3.4745), 1e-2));
@ -1566,4 +1705,80 @@ mod test {
assert!(!b.is_normal());
assert!(_1_1i.is_normal());
}
#[test]
fn test_from_str() {
fn test(z: Complex64, s: &str) {
assert_eq!(FromStr::from_str(s), Ok(z));
}
test(_0_0i, "0 + 0i");
test(_0_0i, "0+0j");
test(_0_0i, "0 - 0j");
test(_0_0i, "0-0i");
test(_0_0i, "0i + 0");
test(_0_0i, "0");
test(_0_0i, "-0");
test(_0_0i, "0i");
test(_0_0i, "0j");
test(_0_0i, "+0j");
test(_0_0i, "-0i");
test(_1_0i, "1 + 0i");
test(_1_0i, "1+0j");
test(_1_0i, "1 - 0j");
test(_1_0i, "+1-0i");
test(_1_0i, "-0j+1");
test(_1_0i, "1");
test(_1_1i, "1 + i");
test(_1_1i, "1+j");
test(_1_1i, "1 + 1j");
test(_1_1i, "1+1i");
test(_1_1i, "i + 1");
test(_1_1i, "1i+1");
test(_1_1i, "+j+1");
test(_0_1i, "0 + i");
test(_0_1i, "0+j");
test(_0_1i, "-0 + j");
test(_0_1i, "-0+i");
test(_0_1i, "0 + 1i");
test(_0_1i, "0+1j");
test(_0_1i, "-0 + 1j");
test(_0_1i, "-0+1i");
test(_0_1i, "j + 0");
test(_0_1i, "i");
test(_0_1i, "j");
test(_0_1i, "1j");
test(_neg1_1i, "-1 + i");
test(_neg1_1i, "-1+j");
test(_neg1_1i, "-1 + 1j");
test(_neg1_1i, "-1+1i");
test(_neg1_1i, "1i-1");
test(_neg1_1i, "j + -1");
test(_05_05i, "0.5 + 0.5i");
test(_05_05i, "0.5+0.5j");
test(_05_05i, "5e-1+0.5j");
test(_05_05i, "5E-1 + 0.5j");
test(_05_05i, "5E-1i + 0.5");
test(_05_05i, "0.05e+1j + 50E-2");
}
#[test]
fn test_from_str_fail() {
fn test(s: &str) {
let complex: Result<Complex64, _> = FromStr::from_str(s);
assert!(complex.is_err());
}
test("foo");
test("6E");
test("0 + 2.718");
test("1 - -2i");
test("314e-2ij");
test("4.3j - i");
test("1i - 2i");
test("+ 1 - 3.0i");
}
}