Implement --numbers fixed

2021-06-04 22:05:48 +10:00 · 2021-06-04 22:05:48 +10:00 · ceba059c53
commit ceba059c53
parent 441e266b17
12 changed files with 472 additions and 106 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@ -96,6 +96,18 @@ dependencies = [
 "wasm-bindgen",
 ]

+[[package]]
+name = "const_fn_assert"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "27d614f23f34f7b5165a77dc1591f497e2518f9cec4b4f4b92bfc4dc6cf7a190"
+
+[[package]]
+name = "convert_case"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6245d59a3e82a7fc217c5828a6692dbc6dfb63a0c8c90495621f7b9d79704a0e"
+
 [[package]]
 name = "crc32fast"
 version = "1.2.1"
@ -127,6 +139,18 @@ dependencies = [
 "memchr",
 ]

+[[package]]
+name = "derive_more"
+version = "0.99.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5cc7b9cef1e351660e5443924e4f43ab25fbbed3e9a5f052df3677deb4d6b320"
+dependencies = [
+ "convert_case",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "flate2"
 version = "1.0.20"
@ -186,6 +210,19 @@ dependencies = [
 "unicode-segmentation",
 ]

+[[package]]
+name = "ibig"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "61c5022ee7f7a2feb0bd2fdc4b8ec882cd14903cebf33e7c1847e3f3a282f8b7"
+dependencies = [
+ "cfg-if 1.0.0",
+ "const_fn_assert",
+ "num-traits",
+ "rand",
+ "static_assertions",
+]
+
 [[package]]
 name = "indexmap"
 version = "1.6.2"
@ -297,8 +334,10 @@ dependencies = [
 "clap",
 "console_error_panic_hook",
 "csv",
+ "derive_more",
 "flate2",
 "git-version",
+ "ibig",
 "js-sys",
 "num-bigint",
 "num-rational",
@ -368,6 +407,21 @@ dependencies = [
 "proc-macro2",
 ]

+[[package]]
+name = "rand"
+version = "0.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0ef9e7e66b4468674bfcb0c81af8b7fa0bb154fa9f28eb840da5c447baeb8d7e"
+dependencies = [
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34cf66eb183df1c5876e2dcf6b13d57340741e8dc255b48e40a26de954d06ae7"
+
 [[package]]
 name = "regex-automata"
 version = "0.1.9"
@ -400,6 +454,12 @@ version = "1.0.126"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ec7505abeacaec74ae4778d9d9328fe5a5d04253220a85c4ee022239fc996d03"

+[[package]]
+name = "static_assertions"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
+
 [[package]]
 name = "syn"
 version = "1.0.72"
--- a/Cargo.toml
+++ b/Cargo.toml
@ -8,7 +8,9 @@ edition = "2018"
 crate-type = ["lib", "cdylib"]

 [dependencies]
+derive_more = "0.99.14"
 git-version = "0.3.4"
+ibig = "0.3.2"
 num-traits = "0.2"
 wasm-bindgen = "0.2.74"

--- a/html/index.html
+++ b/html/index.html
@ -146,18 +146,16 @@
 						<label>
 							Numbers:
 							<select id="selNumbers">
-								<!--<option value="native">Native</option>
 								<option value="rational">Rational</option>
 								<option value="fixed" selected>Fixed</option>
-								<option value="gfixed">Fixed (guarded)</option>-->
-								<option value="rational">Rational</option>
+								<!--<option value="gfixed">Fixed (guarded)</option>-->
 								<option value="float64">Float (64-bit)</option>
 							</select>
 						</label>
-						<!--<label>
-							Decimal places (if Numbers = Fixed):
+						<label>
+							Decimal places (if <i>Numbers</i> = <i>Fixed</i>):
 							<input type="number" id="txtDP" value="5" min="0" style="width: 3em;">
-						</label>-->
+						</label>
 					</div>
 					<div class="col-12">
 						<label>
--- a/html/index.js
+++ b/html/index.js
@ -99,5 +99,6 @@ async function clickCount() {
 		'optsStr': optsStr,
 		'filePath': filePath,
 		'numbers': document.getElementById('selNumbers').value,
+		'decimals': document.getElementById('txtDP').value,
 	});
 }
--- a/html/worker.js
+++ b/html/worker.js
@ -11,10 +11,15 @@ initWasm();
 onmessage = function(evt) {
 	if (evt.data.type === 'countElection') {
 		let numbers;
-		if (evt.data.numbers === 'rational') {
-			numbers = 'Rational';
+		if (evt.data.numbers === 'fixed') {
+			numbers = 'Fixed';
+			wasm.fixed_set_dps(evt.data.decimals);
 		} else if (evt.data.numbers === 'float64') {
 			numbers = 'NativeFloat64';
+		} else if (evt.data.numbers === 'rational') {
+			numbers = 'Rational';
+		} else {
+			throw 'Unknown --numbers';
 		}
 		
 		// Init election
--- a/src/main.rs
+++ b/src/main.rs
@ -17,7 +17,7 @@

 use opentally::stv;
 use opentally::election::{Candidate, CandidateState, CountCard, CountState, CountStateOrRef, Election, StageResult};
-use opentally::numbers::{NativeFloat64, Number, Rational};
+use opentally::numbers::{Fixed, NativeFloat64, Number, Rational};

 use clap::{AppSettings, Clap};

@ -52,9 +52,13 @@ struct STV {
 	// -- Numbers settings --
 	
 	/// Numbers mode
-	#[clap(help_heading=Some("NUMBERS"), short, long, possible_values=&["rational", "float64"], default_value="rational", value_name="mode")]
+	#[clap(help_heading=Some("NUMBERS"), short, long, possible_values=&["rational", "float64", "fixed"], default_value="rational", value_name="mode")]
 	numbers: String,
 	
+	/// Decimal places if --numbers fixed
+	#[clap(help_heading=Some("NUMBERS"), long, default_value="5", value_name="dps")]
+	decimals: usize,
+	
 	// -----------------------
 	// -- Rounding settings --
 	
@ -135,6 +139,10 @@ fn main() {
 	} else if cmd_opts.numbers == "float64" {
 		let election: Election<NativeFloat64> = Election::from_blt(lines.map(|r| r.expect("IO Error").to_string()).into_iter());
 		count_election(election, cmd_opts);
+	} else if cmd_opts.numbers == "fixed" {
+		Fixed::set_dps(cmd_opts.decimals);
+		let election: Election<Fixed> = Election::from_blt(lines.map(|r| r.expect("IO Error").to_string()).into_iter());
+		count_election(election, cmd_opts);
 	}
 }

--- a/src/numbers/fixed.rs
+++ b/src/numbers/fixed.rs
@ -0,0 +1,327 @@
+/*  OpenTally: Open-source election vote counting
+ *  Copyright © 2021 Lee Yingtong Li (RunasSudo)
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+use super::{Assign, From, Number};
+
+use ibig::{IBig, ops::Abs};
+use num_traits::{Num, One, Zero};
+
+use std::cmp::{Ord, PartialEq, PartialOrd};
+use std::ops;
+use std::fmt;
+
+static mut DPS: Option<usize> = None;
+static mut FACTOR: Option<IBig> = None;
+
+#[inline]
+pub fn get_dps() -> usize {
+	unsafe { DPS.unwrap() }
+}
+
+#[inline]
+fn get_factor() -> &'static IBig {
+	unsafe { FACTOR.as_ref().unwrap() }
+}
+
+#[derive(Clone, Eq, Ord, PartialEq, PartialOrd)]
+pub struct Fixed(IBig);
+
+impl Fixed {
+	pub fn set_dps(dps: usize) {
+		unsafe {
+			DPS = Some(dps);
+			FACTOR = Some(IBig::from(10).pow(dps));
+		}
+	}
+}
+
+impl Number for Fixed {
+	fn new() -> Self { Self(IBig::zero()) }
+	
+	fn describe() -> String { format!("--numbers fixed --decimals {}", get_dps()) }
+	
+	fn pow_assign(&mut self, exponent: i32) {
+		self.0 = self.0.pow(exponent as usize) * get_factor() / get_factor().pow(exponent as usize);
+	}
+	
+	fn floor_mut(&mut self, dps: usize) {
+		// Only do something if truncating
+		if dps < get_dps() {
+			let factor = IBig::from(10).pow(get_dps() - dps);
+			self.0 /= &factor;
+			self.0 *= factor;
+		}
+	}
+	
+	fn ceil_mut(&mut self, dps: usize) {
+		// Only do something if truncating
+		if dps < get_dps() {
+			self.0 += IBig::one();
+			let factor = IBig::from(10).pow(get_dps() - dps);
+			self.0 /= &factor;
+			self.0 *= factor;
+		}
+	}
+}
+
+impl Num for Fixed {
+	type FromStrRadixErr = ibig::error::ParseError;
+	fn from_str_radix(str: &str, radix: u32) -> Result<Self, Self::FromStrRadixErr> {
+		match IBig::from_str_radix(str, radix) {
+			Ok(value) => Ok(Self(value * get_factor())),
+			Err(err) => Err(err)
+		}
+	}
+}
+
+impl Assign for Fixed {
+	fn assign(&mut self, src: Self) { self.0 = src.0 }
+}
+
+impl Assign<&Self> for Fixed {
+	fn assign(&mut self, src: &Self) { self.0 = src.0.clone() }
+}
+
+impl From<usize> for Fixed {
+	fn from(n: usize) -> Self { Self(IBig::from(n) * get_factor()) }
+}
+
+impl From<f64> for Fixed {
+	fn from(n: f64) -> Self {
+		return Self(IBig::from((n * 10_f64.powi(get_dps() as i32)) as u32))
+	}
+}
+
+impl fmt::Display for Fixed {
+	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+		let dps = match f.precision() {
+			Some(precision) => if precision < get_dps() { precision } else { get_dps() },
+			None => get_dps(),
+		};
+		
+		let factor = IBig::from(10).pow(get_dps() - dps);
+		let mut result = (&self.0 / factor).abs().to_string();
+		
+		let should_add_minus = (self.0 < IBig::zero()) && result != "0";
+		
+		// Add leading 0s
+		result = format!("{0:0>1$}", result, dps + 1);
+		
+		// Add the decimal point
+		if dps > 0 {
+			result.insert(result.len() - dps, '.');
+		}
+		
+		// Add the sign
+		if should_add_minus {
+			result.insert(0, '-');
+		}
+		
+		return f.write_str(&result);
+	}
+}
+
+impl One for Fixed {
+	fn one() -> Self { Self(get_factor().clone()) }
+}
+
+impl Zero for Fixed {
+	fn zero() -> Self { Self::new() }
+	fn is_zero(&self) -> bool { self.0.is_zero() }
+}
+
+impl ops::Neg for Fixed {
+	type Output = Self;
+	fn neg(self) -> Self::Output { Self(-self.0) }
+}
+
+impl ops::Add for Fixed {
+	type Output = Self;
+	fn add(self, _rhs: Self) -> Self::Output {
+		todo!()
+	}
+}
+
+impl ops::Sub for Fixed {
+	type Output = Self;
+	fn sub(self, _rhs: Self) -> Self::Output {
+		todo!()
+	}
+}
+
+impl ops::Mul for Fixed {
+	type Output = Self;
+	fn mul(self, _rhs: Self) -> Self::Output {
+		todo!()
+	}
+}
+
+impl ops::Div for Fixed {
+	type Output = Self;
+	fn div(self, _rhs: Self) -> Self::Output {
+		todo!()
+	}
+}
+
+impl ops::Rem for Fixed {
+	type Output = Self;
+	fn rem(self, _rhs: Self) -> Self::Output {
+		todo!()
+	}
+}
+
+impl ops::Add<&Self> for Fixed {
+	type Output = Self;
+	fn add(self, rhs: &Self) -> Self::Output { Self(self.0 + &rhs.0) }
+}
+
+impl ops::Sub<&Self> for Fixed {
+	type Output = Self;
+	fn sub(self, _rhs: &Self) -> Self::Output {
+		todo!()
+	}
+}
+
+impl ops::Mul<&Self> for Fixed {
+	type Output = Self;
+	fn mul(self, rhs: &Self) -> Self::Output { Self(self.0 * &rhs.0 / get_factor()) }
+}
+
+impl ops::Div<&Self> for Fixed {
+	type Output = Self;
+	fn div(self, rhs: &Self) -> Self::Output { Self(self.0 * get_factor() / &rhs.0) }
+}
+
+impl ops::Rem<&Self> for Fixed {
+	type Output = Self;
+	fn rem(self, _rhs: &Self) -> Self::Output {
+		todo!()
+	}
+}
+
+impl ops::AddAssign for Fixed {
+	fn add_assign(&mut self, rhs: Self) { self.0 += rhs.0; }
+}
+
+impl ops::SubAssign for Fixed {
+	fn sub_assign(&mut self, rhs: Self) { self.0 -= rhs.0; }
+}
+
+impl ops::MulAssign for Fixed {
+	fn mul_assign(&mut self, rhs: Self) {
+		self.0 *= rhs.0;
+		self.0 /= get_factor();
+	}
+}
+
+impl ops::DivAssign for Fixed {
+	fn div_assign(&mut self, rhs: Self) {
+		self.0 *= get_factor();
+		self.0 /= rhs.0;
+	}
+}
+
+impl ops::RemAssign for Fixed {
+	fn rem_assign(&mut self, _rhs: Self) {
+		todo!()
+	}
+}
+
+impl ops::AddAssign<&Self> for Fixed {
+	fn add_assign(&mut self, rhs: &Self) { self.0 += &rhs.0; }
+}
+
+impl ops::SubAssign<&Self> for Fixed {
+	fn sub_assign(&mut self, rhs: &Self) { self.0 -= &rhs.0; }
+}
+
+impl ops::MulAssign<&Self> for Fixed {
+	fn mul_assign(&mut self, rhs: &Self) {
+		self.0 *= &rhs.0;
+		self.0 /= get_factor();
+	}
+}
+
+impl ops::DivAssign<&Self> for Fixed {
+	fn div_assign(&mut self, _rhs: &Self) {
+		todo!()
+	}
+}
+
+impl ops::RemAssign<&Self> for Fixed {
+	fn rem_assign(&mut self, _rhs: &Self) {
+		todo!()
+	}
+}
+
+impl ops::Neg for &Fixed {
+	type Output = Fixed;
+	fn neg(self) -> Self::Output { Fixed(-&self.0) }
+}
+
+impl ops::Add<Self> for &Fixed {
+	type Output = Fixed;
+	fn add(self, _rhs: Self) -> Self::Output {
+		todo!()
+	}
+}
+
+impl ops::Sub<Self> for &Fixed {
+	type Output = Fixed;
+	fn sub(self, rhs: Self) -> Self::Output { Fixed(&self.0 - &rhs.0) }
+}
+
+impl ops::Mul<Self> for &Fixed {
+	type Output = Fixed;
+	fn mul(self, _rhs: Self) -> Self::Output {
+		todo!()
+	}
+}
+
+impl ops::Div<Self> for &Fixed {
+	type Output = Fixed;
+	fn div(self, rhs: Self) -> Self::Output { Fixed(&self.0 * get_factor() / &rhs.0) }
+}
+
+impl ops::Rem<Self> for &Fixed {
+	type Output = Fixed;
+	fn rem(self, _rhs: Self) -> Self::Output {
+		todo!()
+	}
+}
+
+/*
+impl ops::Add<&&Rational> for &Rational {
+	
+}
+
+impl ops::Sub<&&Rational> for &Rational {
+	
+}
+
+impl ops::Mul<&&Rational> for &Rational {
+	
+}
+
+impl ops::Div<&&Rational> for &Rational {
+	
+}
+
+impl ops::Rem<&&Rational> for &Rational {
+	
+}
+*/
--- a/src/numbers/mod.rs
+++ b/src/numbers/mod.rs
@ -15,6 +15,7 @@
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

+mod fixed;
 mod native;

 #[cfg(not(target_arch = "wasm32"))]
@ -60,6 +61,7 @@ where
 	}
 }

+pub use self::fixed::Fixed;
 pub use self::native::NativeFloat64;

 #[cfg(not(target_arch = "wasm32"))]
--- a/src/numbers/native.rs
+++ b/src/numbers/native.rs
@ -17,15 +17,16 @@

 use super::{Assign, From, Number};

+use derive_more::Display;
 use num_traits::{Num, One, Zero};

 use std::cmp::{Ord, Ordering, PartialEq, PartialOrd};
 use std::num::ParseIntError;
-use std::fmt;
 use std::ops;

 type ImplType = f64;

+#[derive(Clone, Display, PartialEq, PartialOrd)]
 pub struct NativeFloat64(ImplType);

 impl Number for NativeFloat64 {
@ -50,7 +51,6 @@ impl Number for NativeFloat64 {

 impl Num for NativeFloat64 {
 	type FromStrRadixErr = ParseIntError;
-	
 	fn from_str_radix(str: &str, radix: u32) -> Result<Self, Self::FromStrRadixErr> {
 		match i64::from_str_radix(str, radix) {
 			Ok(value) => Ok(Self(value as ImplType)),
@ -75,14 +75,6 @@ impl From<f64> for NativeFloat64 {
 	fn from(n: f64) -> Self { Self(n as ImplType) }
 }

-impl Clone for NativeFloat64 {
-	fn clone(&self) -> Self { Self(self.0) }
-}
-
-impl fmt::Display for NativeFloat64 {
-	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { self.0.fmt(f) }
-}
-
 impl One for NativeFloat64 {
 	fn one() -> Self { Self(1.0) }
 }
@ -93,18 +85,10 @@ impl Zero for NativeFloat64 {
 }

 impl Eq for NativeFloat64 {}
-impl PartialEq for NativeFloat64 {
-	fn eq(&self, other: &Self) -> bool { self.0 == other.0 }
-}
-
 impl Ord for NativeFloat64 {
 	fn cmp(&self, other: &Self) -> Ordering { self.0.partial_cmp(&other.0).unwrap() }
 }

-impl PartialOrd for NativeFloat64 {
-	fn partial_cmp(&self, other: &Self) -> Option<Ordering> { self.0.partial_cmp(&other.0) }
-}
-
 impl ops::Neg for NativeFloat64 {
 	type Output = NativeFloat64;
 	fn neg(self) -> Self::Output { Self(-self.0) }
@ -140,7 +124,6 @@ impl ops::Div for NativeFloat64 {

 impl ops::Rem for NativeFloat64 {
 	type Output = NativeFloat64;
-	
 	fn rem(self, _rhs: Self) -> Self::Output {
 		todo!()
 	}
--- a/src/numbers/rational_num.rs
+++ b/src/numbers/rational_num.rs
@ -25,6 +25,7 @@ use std::cmp::{Ord, Ordering, PartialEq, PartialOrd};
 use std::fmt;
 use std::ops;

+#[derive(Clone, PartialEq, PartialOrd)]
 pub struct Rational(BigRational);

 impl Number for Rational {
@ -60,11 +61,8 @@ impl Number for Rational {
 }

 impl Num for Rational {
-	//type FromStrRadixErr = ParseRatioError;
 	type FromStrRadixErr = ParseBigIntError;
-	
 	fn from_str_radix(str: &str, radix: u32) -> Result<Self, Self::FromStrRadixErr> {
-		//match BigRational::from_str_radix(str, radix) {
 		match BigInt::from_str_radix(str, radix) {
 			Ok(value) => Ok(Self(BigRational::from_integer(value))),
 			Err(err) => Err(err)
@ -91,10 +89,6 @@ impl From<f64> for Rational {
 	}
 }

-impl Clone for Rational {
-	fn clone(&self) -> Self { Self(self.0.clone()) }
-}
-
 impl fmt::Display for Rational {
 	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 		if let Some(precision) = f.precision() {
@ -136,18 +130,10 @@ impl Zero for Rational {
 }

 impl Eq for Rational {}
-impl PartialEq for Rational {
-	fn eq(&self, other: &Self) -> bool { self.0 == other.0 }
-}
-
 impl Ord for Rational {
 	fn cmp(&self, other: &Self) -> Ordering { self.0.partial_cmp(&other.0).unwrap() }
 }

-impl PartialOrd for Rational {
-	fn partial_cmp(&self, other: &Self) -> Option<Ordering> { self.0.partial_cmp(&other.0) }
-}
-
 impl ops::Neg for Rational {
 	type Output = Rational;
 	fn neg(self) -> Self::Output { Self(-self.0) }
@ -183,7 +169,6 @@ impl ops::Div for Rational {

 impl ops::Rem for Rational {
 	type Output = Rational;
-	
 	fn rem(self, _rhs: Self) -> Self::Output {
 		todo!()
 	}
--- a/src/numbers/rational_rug.rs
+++ b/src/numbers/rational_rug.rs
@ -25,6 +25,7 @@ use std::cmp::{Ord, Ordering, PartialEq, PartialOrd};
 use std::fmt;
 use std::ops;

+#[derive(Clone, PartialEq, PartialOrd)]
 pub struct Rational(rug::Rational);

 impl Number for Rational {
@ -61,7 +62,6 @@ impl Number for Rational {

 impl Num for Rational {
 	type FromStrRadixErr = ParseRationalError;
-	
 	fn from_str_radix(str: &str, radix: u32) -> Result<Self, Self::FromStrRadixErr> {
 		match rug::Rational::parse_radix(str, radix as i32) {
 			Ok(value) => Ok(Self(rug::Rational::from(value))),
@ -74,8 +74,8 @@ impl Assign for Rational {
 	fn assign(&mut self, src: Self) { self.0.assign(src.0) }
 }

-impl Assign<&Rational> for Rational {
-	fn assign(&mut self, src: &Rational) { self.0.assign(&src.0) }
+impl Assign<&Self> for Rational {
+	fn assign(&mut self, src: &Self) { self.0.assign(&src.0) }
 }

 impl From<usize> for Rational {
@ -89,10 +89,6 @@ impl From<f64> for Rational {
 	}
 }

-impl Clone for Rational {
-	fn clone(&self) -> Self { Self(self.0.clone()) }
-}
-
 impl fmt::Display for Rational {
 	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 		if let Some(precision) = f.precision() {
@ -134,84 +130,75 @@ impl Zero for Rational {
 }

 impl Eq for Rational {}
-impl PartialEq for Rational {
-	fn eq(&self, other: &Self) -> bool { self.0 == other.0 }
-}
-
 impl Ord for Rational {
 	fn cmp(&self, other: &Self) -> Ordering { self.0.cmp(&other.0) }
 }

-impl PartialOrd for Rational {
-	fn partial_cmp(&self, other: &Self) -> Option<Ordering> { self.0.partial_cmp(&other.0) }
-}
-
 impl ops::Neg for Rational {
-	type Output = Rational;
+	type Output = Self;
 	fn neg(self) -> Self::Output { Self(-self.0) }
 }

 impl ops::Add for Rational {
-	type Output = Rational;
+	type Output = Self;
 	fn add(self, _rhs: Self) -> Self::Output {
 		todo!()
 	}
 }

 impl ops::Sub for Rational {
-	type Output = Rational;
+	type Output = Self;
 	fn sub(self, _rhs: Self) -> Self::Output {
 		todo!()
 	}
 }

 impl ops::Mul for Rational {
-	type Output = Rational;
+	type Output = Self;
 	fn mul(self, _rhs: Self) -> Self::Output {
 		todo!()
 	}
 }

 impl ops::Div for Rational {
-	type Output = Rational;
+	type Output = Self;
 	fn div(self, _rhs: Self) -> Self::Output {
 		todo!()
 	}
 }

 impl ops::Rem for Rational {
-	type Output = Rational;
-	
+	type Output = Self;
 	fn rem(self, _rhs: Self) -> Self::Output {
 		todo!()
 	}
 }

-impl ops::Add<&Rational> for Rational {
-	type Output = Rational;
-	fn add(self, rhs: &Rational) -> Self::Output { Self(self.0 + &rhs.0) }
+impl ops::Add<&Self> for Rational {
+	type Output = Self;
+	fn add(self, rhs: &Self) -> Self::Output { Self(self.0 + &rhs.0) }
 }

-impl ops::Sub<&Rational> for Rational {
-	type Output = Rational;
-	fn sub(self, _rhs: &Rational) -> Self::Output {
+impl ops::Sub<&Self> for Rational {
+	type Output = Self;
+	fn sub(self, _rhs: &Self) -> Self::Output {
 		todo!()
 	}
 }

-impl ops::Mul<&Rational> for Rational {
-	type Output = Rational;
-	fn mul(self, rhs: &Rational) -> Self::Output { Self(self.0 * &rhs.0) }
+impl ops::Mul<&Self> for Rational {
+	type Output = Self;
+	fn mul(self, rhs: &Self) -> Self::Output { Self(self.0 * &rhs.0) }
 }

-impl ops::Div<&Rational> for Rational {
-	type Output = Rational;
-	fn div(self, rhs: &Rational) -> Self::Output { Self(self.0 / &rhs.0) }
+impl ops::Div<&Self> for Rational {
+	type Output = Self;
+	fn div(self, rhs: &Self) -> Self::Output { Self(self.0 / &rhs.0) }
 }

-impl ops::Rem<&Rational> for Rational {
-	type Output = Rational;
-	fn rem(self, _rhs: &Rational) -> Self::Output {
+impl ops::Rem<&Self> for Rational {
+	type Output = Self;
+	fn rem(self, _rhs: &Self) -> Self::Output {
 		todo!()
 	}
 }
@ -238,26 +225,26 @@ impl ops::RemAssign for Rational {
 	}
 }

-impl ops::AddAssign<&Rational> for Rational {
-	fn add_assign(&mut self, rhs: &Rational) { self.0 += &rhs.0 }
+impl ops::AddAssign<&Self> for Rational {
+	fn add_assign(&mut self, rhs: &Self) { self.0 += &rhs.0 }
 }

-impl ops::SubAssign<&Rational> for Rational {
-	fn sub_assign(&mut self, rhs: &Rational) { self.0 -= &rhs.0 }
+impl ops::SubAssign<&Self> for Rational {
+	fn sub_assign(&mut self, rhs: &Self) { self.0 -= &rhs.0 }
 }

-impl ops::MulAssign<&Rational> for Rational {
-	fn mul_assign(&mut self, rhs: &Rational) { self.0 *= &rhs.0 }
+impl ops::MulAssign<&Self> for Rational {
+	fn mul_assign(&mut self, rhs: &Self) { self.0 *= &rhs.0 }
 }

-impl ops::DivAssign<&Rational> for Rational {
-	fn div_assign(&mut self, _rhs: &Rational) {
+impl ops::DivAssign<&Self> for Rational {
+	fn div_assign(&mut self, _rhs: &Self) {
 		todo!()
 	}
 }

-impl ops::RemAssign<&Rational> for Rational {
-	fn rem_assign(&mut self, _rhs: &Rational) {
+impl ops::RemAssign<&Self> for Rational {
+	fn rem_assign(&mut self, _rhs: &Self) {
 		todo!()
 	}
 }
@ -267,33 +254,33 @@ impl ops::Neg for &Rational {
 	fn neg(self) -> Self::Output { Rational(rug::Rational::from(-&self.0)) }
 }

-impl ops::Add<&Rational> for &Rational {
+impl ops::Add<Self> for &Rational {
 	type Output = Rational;
-	fn add(self, _rhs: &Rational) -> Self::Output {
+	fn add(self, _rhs: Self) -> Self::Output {
 		todo!()
 	}
 }

-impl ops::Sub<&Rational> for &Rational {
+impl ops::Sub<Self> for &Rational {
 	type Output = Rational;
-	fn sub(self, rhs: &Rational) -> Self::Output { Rational(rug::Rational::from(&self.0 - &rhs.0)) }
+	fn sub(self, rhs: Self) -> Self::Output { Rational(rug::Rational::from(&self.0 - &rhs.0)) }
 }

-impl ops::Mul<&Rational> for &Rational {
+impl ops::Mul<Self> for &Rational {
 	type Output = Rational;
-	fn mul(self, _rhs: &Rational) -> Self::Output {
+	fn mul(self, _rhs: Self) -> Self::Output {
 		todo!()
 	}
 }

-impl ops::Div<&Rational> for &Rational {
+impl ops::Div<Self> for &Rational {
 	type Output = Rational;
-	fn div(self, rhs: &Rational) -> Self::Output { Rational(rug::Rational::from(&self.0 / &rhs.0)) }
+	fn div(self, rhs: Self) -> Self::Output { Rational(rug::Rational::from(&self.0 / &rhs.0)) }
 }

-impl ops::Rem<&Rational> for &Rational {
+impl ops::Rem<Self> for &Rational {
 	type Output = Rational;
-	fn rem(self, _rhs: &Rational) -> Self::Output {
+	fn rem(self, _rhs: Self) -> Self::Output {
 		todo!()
 	}
 }
--- a/src/stv/wasm.rs
+++ b/src/stv/wasm.rs
@ -16,7 +16,7 @@
 */

 use crate::election::{CandidateState, CountState, Election};
-use crate::numbers::{NativeFloat64, Number, Rational};
+use crate::numbers::{Fixed, NativeFloat64, Number, Rational};
 use crate::stv;

 extern crate console_error_panic_hook;
@ -24,11 +24,18 @@ extern crate console_error_panic_hook;
 use js_sys::Array;
 use wasm_bindgen::prelude::wasm_bindgen;

+// Init
+
+#[wasm_bindgen]
+pub fn fixed_set_dps(dps: usize) {
+	Fixed::set_dps(dps);
+}
+
 // Helper macros for making functions

 macro_rules! impl_type {
 	($type:ident) => { paste::item! {
-		// Exported functions
+		// Counting
 		
 		#[wasm_bindgen]
 		#[allow(non_snake_case)]
@ -119,8 +126,9 @@ macro_rules! impl_type {
 	}}
 }

-impl_type!(Rational);
+impl_type!(Fixed);
 impl_type!(NativeFloat64);
+impl_type!(Rational);

 // Reporting

@ -137,7 +145,7 @@ fn describe_count<N: Number>(filename: String, election: &Election<N>, opts: &st
 	let mut result = String::from("<p>Count computed by OpenTally (revision ");
 	result.push_str(crate::VERSION);
 	let total_ballots = election.ballots.iter().fold(N::zero(), |acc, b| { acc + &b.orig_value });
-	result.push_str(&format!(r#"). Read {} ballots from &lsquo;{}&rsquo; for election &lsquo;{}&rsquo;. There are {} candidates for {} vacancies. Counting using options <span style="font-family: monospace;">{}</span>.</p>"#, total_ballots, filename, election.name, election.candidates.len(), election.seats, opts.describe::<N>()));
+	result.push_str(&format!(r#"). Read {:.dps$} ballots from &lsquo;{}&rsquo; for election &lsquo;{}&rsquo;. There are {} candidates for {} vacancies. Counting using options <span style="font-family: monospace;">{}</span>.</p>"#, total_ballots, filename, election.name, election.candidates.len(), election.seats, opts.describe::<N>(), dps=opts.pp_decimals));
 	return result;
 }