diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index dfc777f..783653c 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -12,7 +12,7 @@ use crate::parser::groupify::groupify;
 use crate::parser::treeify::treeify;
 use crate::parser::find_subs::find_subs;
 
-use crate::quantity::Quantity;
+use crate::quantity::{Quantity, BaseUnit};
 
 use crate::tokens::Token;
 
@@ -96,6 +96,19 @@ impl PreToken {
 					"e" => { Token::Constant(Quantity::new_float_from_string("2.718281828459045235360287471352662497757247093699959574966967627724076630353547594571382178525166427").unwrap(), String::from("e")) },
 					"phi"|"φ" => { Token::Constant(Quantity::new_float_from_string("1.618033988749894848204586834365638117720309179805762862135448622705260462818902449707207204189391137").unwrap(), String::from("φ")) },
 
+					// Units
+					"m" => {
+						let mut u = Quantity::new_rational(1, 1);
+						u.add_unit(BaseUnit::Meter, 1f64);
+						Token::Number(u)
+					},
+
+					"s" => {
+						let mut u = Quantity::new_rational(1, 1);
+						u.add_unit(BaseUnit::Second, 1f64);
+						Token::Number(u)
+					}
+
 					_ => { return Err((l, ParserError::Undefined(s))); }
 				});
 			}
diff --git a/src/quantity/floatq.rs b/src/quantity/floatq.rs
index d50796d..a2d275e 100644
--- a/src/quantity/floatq.rs
+++ b/src/quantity/floatq.rs
@@ -13,8 +13,6 @@ use std::ops::{
 
 use std::cmp::Ordering;
 
-use crate::quantity::wrap_float;
-use crate::quantity::Quantity;
 use crate::quantity::QuantBase;
 use crate::quantity::FloatBase;
 use crate::quantity::PRINT_LEN;
@@ -24,8 +22,8 @@ use super::FLOAT_PRECISION;
 
 macro_rules! foward {
 	( $x:ident ) => {
-		fn $x(&self) -> Quantity {
-			wrap_float!(FloatQ{ val: self.val.clone().$x()})
+		fn $x(&self) -> Option<FloatQ> {
+			Some(FloatQ{ val: self.val.clone().$x()})
 		}
 	}
 }
@@ -135,17 +133,12 @@ impl QuantBase for FloatQ {
 	foward!(log10);
 	foward!(log2);
 
-	fn log(&self, base: Quantity) -> Quantity {
-		wrap_float!(FloatQ{ val: self.val.clone().log10() }) /
-		Quantity::float_from_rat(&base).log10()
+	fn log(&self, base: FloatQ) -> Option<FloatQ> {
+		Some(FloatQ{ val: self.val.clone().log10() } / base.log10().unwrap())
 	}
 
-	fn pow(&self, base: Quantity) -> Quantity {
-		match base {
-			Quantity::Rational { .. } => self.pow(Quantity::float_from_rat(&base)),
-			Quantity::Float { v } => wrap_float!(FloatQ{ val: self.val.clone().pow(v.val)})
-		}
-		
+	fn pow(&self, base: FloatQ) -> Option<FloatQ> {
+		Some(FloatQ{ val: self.val.clone().pow(base.val)})
 	}
 
 }
@@ -242,8 +235,8 @@ impl Rem<FloatQ> for FloatQ {
 
 	fn rem(self, modulus: FloatQ) -> Self::Output {
 		if {
-			(!self.fract().is_zero()) ||
-			(!modulus.fract().is_zero())
+			(!self.fract().unwrap().is_zero()) ||
+			(!modulus.fract().unwrap().is_zero())
 		} { panic!() }
 
 		FloatQ{val : self.val.fract() % modulus.val.fract()}
diff --git a/src/quantity/mod.rs b/src/quantity/mod.rs
index c018aff..18b7aa2 100644
--- a/src/quantity/mod.rs
+++ b/src/quantity/mod.rs
@@ -25,6 +25,9 @@ cross-compilation to other systems. RUG does not work on all systems.
 */
 
 pub mod quantity;
+mod unit;
+pub use crate::quantity::unit::Unit;
+pub use crate::quantity::unit::BaseUnit;
 
 cfg_if::cfg_if! {
 	if #[cfg(target_family = "unix")] {
@@ -36,11 +39,11 @@ cfg_if::cfg_if! {
 }
 
 macro_rules! wrap_rational {
-	( $x:expr ) => { Quantity::Rational{v: $x} }
+	( $x:expr, $y:expr ) => { Quantity::Rational{v: $x, u: $y} }
 }
 
 macro_rules! wrap_float {
-	( $x:expr ) => { Quantity::Float{v: $x} }
+	( $x:expr, $y:expr ) => { Quantity::Float{v: $x, u: $y} }
 }
 
 pub use crate::quantity::quantity::Quantity;
@@ -72,31 +75,31 @@ pub trait QuantBase:
 	Neg + Rem +
 	PartialEq + PartialOrd
 {
-	fn fract(&self) -> Quantity;
+	fn fract(&self) -> Option<Self>;
 	fn is_zero(&self) -> bool;
 	fn is_negative(&self) -> bool;
 	fn is_positive(&self) -> bool;
 
-	fn exp(&self) -> Quantity;
-	fn abs(&self) -> Quantity;
-	fn floor(&self) -> Quantity;
-	fn ceil(&self) -> Quantity;
-	fn round(&self) -> Quantity;
-	fn sin(&self) -> Quantity;
-	fn cos(&self) -> Quantity;
-	fn tan(&self) -> Quantity;
-	fn asin(&self) -> Quantity;
-	fn acos(&self) -> Quantity;
-	fn atan(&self) -> Quantity;
-	fn sinh(&self) -> Quantity;
-	fn cosh(&self) -> Quantity;
-	fn tanh(&self) -> Quantity;
-	fn asinh(&self) -> Quantity;
-	fn acosh(&self) -> Quantity;
-	fn atanh(&self) -> Quantity;
-	fn ln(&self) -> Quantity;
-	fn log10(&self) -> Quantity;
-	fn log2(&self) -> Quantity;
-	fn log(&self, base: Quantity) -> Quantity;
-	fn pow(&self, exp: Quantity) -> Quantity;
+	fn exp(&self) -> Option<Self>;
+	fn abs(&self) -> Option<Self>;
+	fn floor(&self) -> Option<Self>;
+	fn ceil(&self) -> Option<Self>;
+	fn round(&self) -> Option<Self>;
+	fn sin(&self) -> Option<Self>;
+	fn cos(&self) -> Option<Self>;
+	fn tan(&self) -> Option<Self>;
+	fn asin(&self) -> Option<Self>;
+	fn acos(&self) -> Option<Self>;
+	fn atan(&self) -> Option<Self>;
+	fn sinh(&self) -> Option<Self>;
+	fn cosh(&self) -> Option<Self>;
+	fn tanh(&self) -> Option<Self>;
+	fn asinh(&self) -> Option<Self>;
+	fn acosh(&self) -> Option<Self>;
+	fn atanh(&self) -> Option<Self>;
+	fn ln(&self) -> Option<Self>;
+	fn log10(&self) -> Option<Self>;
+	fn log2(&self) -> Option<Self>;
+	fn log(&self, base: Self) -> Option<Self>;
+	fn pow(&self, exp: Self) -> Option<Self>;
 }
\ No newline at end of file
diff --git a/src/quantity/quantity.rs b/src/quantity/quantity.rs
index 9a6d2b3..70b1e99 100644
--- a/src/quantity/quantity.rs
+++ b/src/quantity/quantity.rs
@@ -14,6 +14,8 @@ use crate::quantity::QuantBase;
 use crate::quantity::RationalBase;
 use crate::quantity::FloatBase;
 
+use crate::quantity::Unit;
+use crate::quantity::BaseUnit;
 
 cfg_if::cfg_if! {
 	if #[cfg(target_family = "unix")] {
@@ -23,8 +25,8 @@ cfg_if::cfg_if! {
 		#[derive(Debug)]
 		#[derive(Clone)]
 		pub enum Quantity {
-			Rational{ v: RationalQ },
-			Float{ v: FloatQ }
+			Rational{ v: RationalQ, u: Unit },
+			Float{ v: FloatQ, u: Unit }
 		}
 	} else {
 		use crate::quantity::f64q::F64Q;
@@ -32,8 +34,8 @@ cfg_if::cfg_if! {
 		#[derive(Debug)]
 		#[derive(Clone)]
 		pub enum Quantity {
-			Rational{ v: F64Q },
-			Float{ v: F64Q }
+			Rational{ v: F64Q, u: Unit },
+			Float{ v: F64Q, u: Unit }
 		}
 	}
 }
@@ -44,31 +46,44 @@ impl Quantity {
 	cfg_if::cfg_if! {
 		if #[cfg(target_family = "unix")] {
 			pub fn new_rational(top: i64, bottom: i64) -> Quantity {
-				return wrap_rational!(RationalQ::from_frac(top, bottom));
+				return wrap_rational!(
+					RationalQ::from_frac(top, bottom),
+					Unit::new()
+				);
 			}
 		
 			pub fn new_float(v: f64) -> Quantity {
-				return wrap_float!(FloatQ::from_f64(v).unwrap())
+				return wrap_float!(
+					FloatQ::from_f64(v).unwrap(),
+					Unit::new()
+				)
 			}
 		
 			pub fn new_rational_from_string(s: &str) -> Option<Quantity> {
 				let r = RationalQ::from_string(s);
 				if r.is_none() { return None; }
-				return Some(wrap_rational!(r.unwrap()));
+				return Some(wrap_rational!(
+					r.unwrap(),
+					Unit::new()
+				));
 			}
 		
 			pub fn new_float_from_string(s: &str) -> Option<Quantity> {
 				let v = FloatQ::from_string(s);
 				if v.is_none() { return None; }
-				return Some(wrap_float!(v.unwrap()))
+				return Some(wrap_float!(
+					v.unwrap(),
+					Unit::new()
+				))
 			}
 
 			pub fn float_from_rat(r: &Quantity) -> Quantity {
 				match &r {
 					Quantity::Float { .. } => r.clone(),
-					Quantity::Rational { v } => wrap_float!(
+					Quantity::Rational { v, u } => wrap_float!(
 						FloatQ::from(v.val.numer()).unwrap() /
-						FloatQ::from(v.val.denom()).unwrap()
+						FloatQ::from(v.val.denom()).unwrap(),
+						u.clone()
 					)
 				}
 			}
@@ -102,61 +117,93 @@ impl Quantity {
 		}
 	}
 
-
-
-
-
 	pub fn is_nan(&self) -> bool {
 		match self {
-			Quantity::Float { v } => {v.val.is_nan()},
+			Quantity::Float { v, .. } => {v.val.is_nan()},
 			Quantity::Rational { .. } => {panic!()}
 		}
 	}
+
+	pub fn add_unit(&mut self, ui: BaseUnit, pi: f64) {
+		match self {
+			Quantity::Float { u, .. } => {u.insert(ui, pi)},
+			Quantity::Rational { u, .. } => {u.insert(ui, pi)}
+		}
+	}
 }
 
 
 
 impl ToString for Quantity {
 	fn to_string(&self) -> String {
+		let mut n: String;
+		let u: &Unit;
 		match self {
-			Quantity::Rational{v} => v.to_string(),
-			Quantity::Float{v} => v.to_string(),
-		}
+			Quantity::Rational{u:un, ..} => {
+				n = Quantity::float_from_rat(self).to_string();
+				u = un
+			},
+			Quantity::Float{v, u:un} => {
+				n = v.to_string();
+				u = un;
+			},
+		};
+
+		//n.push(' ');
+		//n.push_str(&u.to_string());
+		n
 	}
 }
 
 
 macro_rules! quant_foward {
 	( $x:ident ) => {
-		fn $x(&self) -> Quantity {
+		pub fn $x(&self) -> Quantity {
 			match self {
-				Quantity::Rational{v} => v.$x(),
-				Quantity::Float{v} => v.$x(),
+				Quantity::Rational{v, u} => {
+					if !u.unitless() { panic!() }
+					let r = v.$x();
+					if r.is_none() {
+						let v = Quantity::float_from_rat(self);
+						return v.$x();
+					} else {wrap_rational!(r.unwrap(), u.clone())}
+				},
+				Quantity::Float{v, u} => {
+					if !u.unitless() { panic!() }
+					wrap_float!(v.$x().unwrap(), u.clone())
+				},
 			}
 		}
 	}
 }
 
-impl QuantBase for Quantity {
+impl Quantity {
 
-	fn is_zero(&self) -> bool {
+	pub fn is_zero(&self) -> bool {
 		match self {
-			Quantity::Rational{v} => v.is_zero(),
-			Quantity::Float{v} => v.is_zero(),
+			Quantity::Rational{v, .. } => v.is_zero(),
+			Quantity::Float{v, .. } => v.is_zero(),
 		}
 	}
 
-	fn is_negative(&self) -> bool {
+	pub fn is_negative(&self) -> bool {
 		match self {
-			Quantity::Rational{v} => v.is_negative(),
-			Quantity::Float{v} => v.is_negative(),
+			Quantity::Rational{v, .. } => v.is_negative(),
+			Quantity::Float{v, .. } => v.is_negative(),
 		}
 	}
 
-	fn is_positive(&self) -> bool {
+	pub fn is_positive(&self) -> bool {
 		match self {
-			Quantity::Rational{v} => v.is_positive(),
-			Quantity::Float{v} => v.is_positive(),
+			Quantity::Rational{v, .. } => v.is_positive(),
+			Quantity::Float{v, .. } => v.is_positive(),
+		}
+	}
+
+	pub fn unitless(&self) -> bool {
+		match self {
+			Quantity::Rational{ u, .. } => u.unitless(),
+			Quantity::Float{ u, .. } => u.unitless(),
 		}
 	}
 
@@ -182,16 +229,55 @@ impl QuantBase for Quantity {
 	quant_foward!(log10);
 	quant_foward!(log2);
 
-	fn log(&self, base: Quantity) -> Quantity {
+	pub fn log(&self, base: Quantity) -> Quantity {
+
+		if !self.unitless() { panic!() }
+		
 		match self {
-			Quantity::Rational{v} => v.log(base),
-			Quantity::Float{v} => v.log(base),
+			Quantity::Rational{u, .. } => {
+				if !u.unitless() { panic!() }
+				Quantity::float_from_rat(self).log(Quantity::float_from_rat(&base))
+			},
+			Quantity::Float{u, .. } => {
+				if !u.unitless() { panic!() }
+				Quantity::float_from_rat(self).log(base)
+			},
 		}
 	}
-	fn pow(&self, base: Quantity) -> Quantity {
+	pub fn pow(&self, base: Quantity) -> Quantity {
 		match self {
-			Quantity::Rational{v} => v.pow(base),
-			Quantity::Float{v} => v.pow(base),
+			Quantity::Rational{u, .. } => {
+				let a = match Quantity::float_from_rat(self) {
+					Quantity::Rational{ .. } => panic!(),
+					Quantity::Float{v, .. } => v,
+				};
+
+				let b = match Quantity::float_from_rat(&base) {
+					Quantity::Rational{ .. } => panic!(),
+					Quantity::Float{v, .. } => v,
+				};
+
+				let mut nu = u.clone();
+				nu.pow(2f64);
+				wrap_float!(a.pow(b).unwrap(), nu)
+			},
+			Quantity::Float{u, .. } => {
+				if !u.unitless() { panic!() }
+
+				let a = match Quantity::float_from_rat(self) {
+					Quantity::Rational{ .. } => panic!(),
+					Quantity::Float{v, .. } => v,
+				};
+
+				let b = match Quantity::float_from_rat(&base) {
+					Quantity::Rational{ .. } => panic!(),
+					Quantity::Float{v, .. } => v,
+				};
+				let mut nu = u.clone();
+				nu.pow(2f64);
+				wrap_float!(a.pow(b).unwrap(), nu)
+
+			},
 		}
 	}
 }
@@ -203,8 +289,8 @@ impl Neg for Quantity where {
 
 	fn neg(self) -> Self::Output {
 		match self {
-			Quantity::Float { v } => {wrap_float!(-v)},
-			Quantity::Rational { v } => {wrap_rational!(-v)},
+			Quantity::Float { v, u } => {wrap_float!(-v, u)},
+			Quantity::Rational { v, u } => {wrap_rational!(-v, u)},
 		}
 	}
 }
@@ -214,10 +300,16 @@ impl Add for Quantity {
 
 	fn add(self, other: Self) -> Self::Output {
 		match (&self, &other) {
-			(Quantity::Float{v:a}, Quantity::Float{v:b}) => {wrap_float!(a.clone()+b.clone())},
+			(Quantity::Float{v:va,u:ua}, Quantity::Float{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				wrap_float!(va.clone()+vb.clone(), ua.clone())
+			},
 			(Quantity::Float{ .. }, Quantity::Rational{ .. }) => {self + Quantity::float_from_rat(&other)},
 			(Quantity::Rational{ .. }, Quantity::Float{ .. }) => {Quantity::float_from_rat(&self) + other},
-			(Quantity::Rational{v:a}, Quantity::Rational{v:b}) => {wrap_rational!(a.clone()+b.clone())},
+			(Quantity::Rational{v:va,u:ua}, Quantity::Rational{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				wrap_rational!(va.clone()+vb.clone(), ua.clone())
+			},
 		}
 	}
 }
@@ -225,10 +317,16 @@ impl Add for Quantity {
 impl AddAssign for Quantity where {
 	fn add_assign(&mut self, other: Self) {
 		match (&mut *self, &other) {
-			(Quantity::Float{v: a}, Quantity::Float{v: ref b}) => {*a += b.clone()},
+			(Quantity::Float{v:va,u:ua}, Quantity::Float{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				*va += vb.clone()
+			},
 			(Quantity::Float{ .. }, Quantity::Rational{ .. }) => {*self += Quantity::float_from_rat(&other)},
 			(Quantity::Rational{ .. }, Quantity::Float{ .. }) => {*self = Quantity::float_from_rat(self) + other },
-			(Quantity::Rational{v:a}, Quantity::Rational{v:b}) => {*a += b.clone()},
+			(Quantity::Rational{v:va,u:ua}, Quantity::Rational{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				*va += vb.clone()
+			},
 		}
 	}
 }
@@ -238,10 +336,16 @@ impl Sub for Quantity {
 
 	fn sub(self, other: Self) -> Self::Output {
 		match (&self, &other) {
-			(Quantity::Float{v:a}, Quantity::Float{v:b}) => {wrap_float!(a.clone()-b.clone())},
+			(Quantity::Float{v:va,u:ua}, Quantity::Float{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				wrap_float!(va.clone()-vb.clone(), ua.clone())
+			},
 			(Quantity::Float{ .. }, Quantity::Rational{ .. }) => {self - Quantity::float_from_rat(&other)},
 			(Quantity::Rational{ .. }, Quantity::Float{ .. }) => {Quantity::float_from_rat(&self) - other},
-			(Quantity::Rational{v:a}, Quantity::Rational{v:b}) => {wrap_rational!(a.clone()-b.clone())},
+			(Quantity::Rational{v:va,u:ua}, Quantity::Rational{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				wrap_rational!(va.clone()-vb.clone(), ua.clone())
+			},
 		}
 	}
 }
@@ -249,10 +353,16 @@ impl Sub for Quantity {
 impl SubAssign for Quantity where {
 	fn sub_assign(&mut self, other: Self) {
 		match (&mut *self, &other) {
-			(Quantity::Float{v: a}, Quantity::Float{v: ref b}) => {*a -= b.clone()},
+			(Quantity::Float{v:va,u:ua}, Quantity::Float{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				*va -= vb.clone()
+			},
 			(Quantity::Float{ .. }, Quantity::Rational{ .. }) => {*self -= Quantity::float_from_rat(&other)},
 			(Quantity::Rational{ .. }, Quantity::Float{ .. }) => {*self = Quantity::float_from_rat(self) - other },
-			(Quantity::Rational{v:a}, Quantity::Rational{v:b}) => {*a -= b.clone()},
+			(Quantity::Rational{v:va,u:ua}, Quantity::Rational{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				*va -= vb.clone()
+			},
 		}
 	}
 }
@@ -262,10 +372,16 @@ impl Mul for Quantity {
 
 	fn mul(self, other: Self) -> Self::Output {
 		match (&self, &other) {
-			(Quantity::Float{v:a}, Quantity::Float{v:b}) => {wrap_float!(a.clone()*b.clone())},
+			(Quantity::Float{v:va,u:ua}, Quantity::Float{v:vb,u:ub}) => {
+				let u = ua.clone()*ub.clone();
+				wrap_float!(va.clone()*vb.clone(), u)
+			},
 			(Quantity::Float{ .. }, Quantity::Rational{ .. }) => {self * Quantity::float_from_rat(&other)},
 			(Quantity::Rational{ .. }, Quantity::Float{ .. }) => {Quantity::float_from_rat(&self) * self},
-			(Quantity::Rational{v:a}, Quantity::Rational{v:b}) => {wrap_rational!(a.clone()*b.clone())},
+			(Quantity::Rational{v:va,u:ua}, Quantity::Rational{v:vb,u:ub}) => {
+				let u = ua.clone()*ub.clone();
+				wrap_rational!(va.clone()*vb.clone(), u)
+			},
 		}
 	}
 }
@@ -273,10 +389,16 @@ impl Mul for Quantity {
 impl MulAssign for Quantity where {
 	fn mul_assign(&mut self, other: Self) {
 		match (&mut *self, &other) {
-			(Quantity::Float{v: a}, Quantity::Float{v:b}) => {*a *= b.clone()},
+			(Quantity::Float{v:va,u:ua}, Quantity::Float{v:vb,u:ub}) => {
+				*ua *= ub.clone();
+				*va *= vb.clone()
+			},
 			(Quantity::Float{ .. }, Quantity::Rational{ .. }) => {*self *= Quantity::float_from_rat(&other)},
 			(Quantity::Rational{ .. }, Quantity::Float{ .. }) => {*self = Quantity::float_from_rat(self) * other },
-			(Quantity::Rational{v:a}, Quantity::Rational{v:b}) => {*a *= b.clone()},
+			(Quantity::Rational{v:va,u:ua}, Quantity::Rational{v:vb,u:ub}) => {
+				*ua *= ub.clone();
+				*va *= vb.clone()
+			},
 		}
 	}
 }
@@ -286,10 +408,16 @@ impl Div for Quantity {
 
 	fn div(self, other: Self) -> Self::Output {
 		match (&self, &other) {
-			(Quantity::Float{v:a}, Quantity::Float{v:b}) => {wrap_float!(a.clone()/b.clone())},
+			(Quantity::Float{v:va,u:ua}, Quantity::Float{v:vb,u:ub}) => {
+				let u = ua.clone()/ub.clone();
+				wrap_float!(va.clone()/vb.clone(), u)
+			},
 			(Quantity::Float{ .. }, Quantity::Rational{ .. }) => {self / Quantity::float_from_rat(&other)},
 			(Quantity::Rational{ .. }, Quantity::Float{ .. }) => {Quantity::float_from_rat(&self) / other},
-			(Quantity::Rational{v:a}, Quantity::Rational{v:b}) => {wrap_rational!(a.clone()/b.clone())},
+			(Quantity::Rational{v:va,u:ua}, Quantity::Rational{v:vb,u:ub}) => {
+				let u = ua.clone()/ub.clone();
+				wrap_rational!(va.clone()/vb.clone(), u)
+			},
 		}
 	}
 }
@@ -297,10 +425,16 @@ impl Div for Quantity {
 impl DivAssign for Quantity where {
 	fn div_assign(&mut self, other: Self) {
 		match (&mut *self, &other) {
-			(Quantity::Float{v: a}, Quantity::Float{v: ref b}) => {*a /= b.clone()},
+			(Quantity::Float{v:va,u:ua}, Quantity::Float{v:vb,u:ub}) => {
+				*ua /= ub.clone();
+				*va /= vb.clone()
+			},
 			(Quantity::Float{ .. }, Quantity::Rational{ .. }) => {*self /= Quantity::float_from_rat(&other)},
 			(Quantity::Rational{ .. }, Quantity::Float{ .. }) => {*self = Quantity::float_from_rat(self) / other },
-			(Quantity::Rational{v:a}, Quantity::Rational{v:b}) => {*a /= b.clone()},
+			(Quantity::Rational{v:va,u:ua}, Quantity::Rational{v:vb,u:ub}) => {
+				*ua /= ub.clone();
+				*va /= vb.clone()
+			}
 		}
 	}
 }
@@ -310,10 +444,16 @@ impl Rem<Quantity> for Quantity {
 
 	fn rem(self, other: Quantity) -> Self::Output {
 		match (&self, &other) {
-			(Quantity::Float{v:a}, Quantity::Float{v:b}) => {wrap_float!(a.clone()%b.clone())},
+			(Quantity::Float{v:va,u:ua}, Quantity::Float{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				wrap_float!(va.clone()%vb.clone(), ua.clone())
+			},
 			(Quantity::Float{ .. }, Quantity::Rational{ .. }) => {self % Quantity::float_from_rat(&other)},
 			(Quantity::Rational{ .. }, Quantity::Float{ .. }) => {Quantity::float_from_rat(&self) % other},
-			(Quantity::Rational{v:a}, Quantity::Rational{v:b}) => {wrap_rational!(a.clone()%b.clone())},
+			(Quantity::Rational{v:va,u:ua}, Quantity::Rational{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				wrap_rational!(va.clone()%vb.clone(), ua.clone())
+			},
 		}
 	}
 }
@@ -321,10 +461,10 @@ impl Rem<Quantity> for Quantity {
 impl PartialEq for Quantity {
 	fn eq(&self, other: &Self) -> bool {
 		match (self, other) {
-			(Quantity::Float{v:a}, Quantity::Float{v:b}) => {a == b},
+			(Quantity::Float{v:va,u:ua}, Quantity::Float{v:vb,u:ub}) => { if ua!=ub {false} else {va == vb} },
 			(Quantity::Float{ .. }, Quantity::Rational{ .. }) => {*self == Quantity::float_from_rat(other)},
 			(Quantity::Rational{ .. }, Quantity::Float{ .. }) => {Quantity::float_from_rat(self) == *other},
-			(Quantity::Rational{v:a}, Quantity::Rational{v:b}) => {a == b},
+			(Quantity::Rational{v:va,u:ua}, Quantity::Rational{v:vb,u:ub}) => { if ua!=ub {false} else {va == vb} },
 		}
 	}
 }
@@ -332,10 +472,16 @@ impl PartialEq for Quantity {
 impl PartialOrd for Quantity {
 	fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
 		match (self, other) {
-			(Quantity::Float{v:a}, Quantity::Float{v:b}) => {a.partial_cmp(b)},
+			(Quantity::Float{v:va,u:ua}, Quantity::Float{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				va.partial_cmp(vb)
+			},
 			(Quantity::Float{ .. }, Quantity::Rational{ .. }) => {(*self).partial_cmp(&Quantity::float_from_rat(other))},
 			(Quantity::Rational{ .. }, Quantity::Float{ .. }) => {Quantity::float_from_rat(self).partial_cmp(other)},
-			(Quantity::Rational{v:a}, Quantity::Rational{v:b}) => {a.partial_cmp(b)},
+			(Quantity::Rational{v:va,u:ua}, Quantity::Rational{v:vb,u:ub}) => {
+				if ua != ub { panic!() }
+				va.partial_cmp(vb)
+			},
 		}
 	}
 }
\ No newline at end of file
diff --git a/src/quantity/rationalq.rs b/src/quantity/rationalq.rs
index 7016f20..bc1a130 100644
--- a/src/quantity/rationalq.rs
+++ b/src/quantity/rationalq.rs
@@ -11,17 +11,13 @@ use std::ops::{
 
 use std::cmp::Ordering;
 
-use crate::quantity::wrap_rational;
-use crate::quantity::Quantity;
 use crate::quantity::QuantBase;
 use crate::quantity::RationalBase;
 
 
-macro_rules! float_foward {
+macro_rules! cant_do {
 	( $x:ident ) => {
-		fn $x(&self) -> Quantity {
-			Quantity::float_from_rat(&wrap_rational!(self.clone())).$x()
-		}
+		fn $x(&self) -> Option<RationalQ> { None }
 	}
 }
 
@@ -43,52 +39,46 @@ fn to_sign_string_exp(&self, radix: i32, num_digits: Option<usize>) -> (bool, St
 
 impl ToString for RationalQ{
 	fn to_string(&self) -> String {
-		let v = Quantity::float_from_rat(&wrap_rational!(self.clone()));
-		return v.to_string();
+		return self.val.to_string();
 	}
 }
 
 impl QuantBase for RationalQ {
 
-	fn fract(&self) -> Quantity {
-		wrap_rational!(RationalQ{val: self.val.clone().fract_floor(Integer::new()).0})
+	fn fract(&self) -> Option<RationalQ> {
+		Some(RationalQ{val: self.val.clone().fract_floor(Integer::new()).0})
 	}
 
 	fn is_zero(&self) -> bool {self.val == Rational::from((0,1))}
 	fn is_negative(&self) -> bool { self.val.clone().signum() == -1 }
 	fn is_positive(&self) -> bool { self.val.clone().signum() == 1 }
 
-	fn abs(&self) -> Quantity {wrap_rational!(RationalQ{val: self.val.clone().abs()})}
-	fn floor(&self) -> Quantity {wrap_rational!(RationalQ{val: self.val.clone().floor()})}
-	fn ceil(&self) -> Quantity {wrap_rational!(RationalQ{val: self.val.clone().ceil()})}
-	fn round(&self) -> Quantity {wrap_rational!(RationalQ{val: self.val.clone().round()})}
+	fn abs(&self) -> Option<RationalQ> {Some(RationalQ{val: self.val.clone().abs()})}
+	fn floor(&self) -> Option<RationalQ> {Some(RationalQ{val: self.val.clone().floor()})}
+	fn ceil(&self) -> Option<RationalQ> {Some(RationalQ{val: self.val.clone().ceil()})}
+	fn round(&self) -> Option<RationalQ> {Some(RationalQ{val: self.val.clone().round()})}
 
-	float_foward!(sin);
-	float_foward!(cos);
-	float_foward!(tan);
-	float_foward!(asin);
-	float_foward!(acos);
-	float_foward!(atan);
+	cant_do!(sin);
+	cant_do!(cos);
+	cant_do!(tan);
+	cant_do!(asin);
+	cant_do!(acos);
+	cant_do!(atan);
 
-	float_foward!(sinh);
-	float_foward!(cosh);
-	float_foward!(tanh);
-	float_foward!(asinh);
-	float_foward!(acosh);
-	float_foward!(atanh);
+	cant_do!(sinh);
+	cant_do!(cosh);
+	cant_do!(tanh);
+	cant_do!(asinh);
+	cant_do!(acosh);
+	cant_do!(atanh);
 
-	float_foward!(exp);
-	float_foward!(ln);
-	float_foward!(log10);
-	float_foward!(log2);
+	cant_do!(exp);
+	cant_do!(ln);
+	cant_do!(log10);
+	cant_do!(log2);
 
-	fn log(&self, base: Quantity) -> Quantity {
-		Quantity::float_from_rat(&wrap_rational!(self.clone())).log10() / base.log10()
-	}
-
-	fn pow(&self, base: Quantity) -> Quantity {
-		Quantity::float_from_rat(&wrap_rational!(self.clone())).pow(base)
-	}
+	fn log(&self, _base: RationalQ) -> Option<RationalQ> { None }
+	fn pow(&self, _base: RationalQ) -> Option<RationalQ> { None }
 
 }
 
diff --git a/src/quantity/unit.rs b/src/quantity/unit.rs
new file mode 100644
index 0000000..28abd1e
--- /dev/null
+++ b/src/quantity/unit.rs
@@ -0,0 +1,112 @@
+use std::{collections::HashMap, hash::Hash};
+
+
+use std::ops::{
+	Mul, Div,
+	MulAssign, DivAssign
+};
+
+#[derive(Debug)]
+#[derive(Hash)]
+#[derive(Eq, PartialEq)]
+#[derive(Copy, Clone)]
+pub enum BaseUnit {
+	Second,
+	Meter,
+	Kilogram,
+	Ampere,
+	Kelvin,
+	Mole,
+	Candela
+}
+
+#[derive(Debug)]
+#[derive(Clone)]
+pub struct Unit {
+	// Unit, power.
+	pub val: HashMap<BaseUnit, f64>
+}
+
+
+impl ToString for Unit {
+	fn to_string(&self) -> String {
+		format!("{:?}", self)
+	}
+}
+
+
+impl Unit {
+
+	pub fn new() -> Unit {
+		return Unit{
+			val: HashMap::new()
+		}
+	}
+
+	pub fn unitless(&self) -> bool { self.val.len() == 0 }
+
+	pub fn insert(&mut self, u: BaseUnit, p: f64) {
+		match self.val.get_mut(&u) {
+			Some(i) => {
+				let n = *i + p;
+
+				if n == 0f64 {
+					self.val.remove(&u);
+				} else { *i = n; }
+			},
+			None => { self.val.insert(u, p); }
+		};
+	}
+
+	pub fn pow(&mut self, pwr: f64) {
+		for (_, p) in &mut self.val {
+			*p *= pwr;
+		}
+	}
+
+}
+
+
+impl PartialEq for Unit {
+	fn eq(&self, other: &Self) -> bool {
+		for (u, p) in &other.val {
+			match self.val.get(u) {
+				Some(i) => { if i != p { return false; } },
+				None => { return false; }
+			};
+		}
+		return true;
+	}
+}
+
+impl Mul for Unit {
+	type Output = Self;
+
+	fn mul(self, other: Self) -> Self::Output {
+		let mut o = self.clone();
+		for (u, p) in &other.val { o.insert(*u, *p); }
+		return o;
+	}
+}
+
+impl MulAssign for Unit where {
+	fn mul_assign(&mut self, other: Self) {
+		for (u, p) in &other.val { self.insert(*u, *p); }
+	}
+}
+
+impl Div for Unit {
+	type Output = Self;
+
+	fn div(self, other: Self) -> Self::Output {
+		let mut o = self.clone();
+		for (u, p) in &other.val { o.insert(*u, -*p); }
+		return o;
+	}
+}
+
+impl DivAssign for Unit where {
+	fn div_assign(&mut self, other: Self) {
+		for (u, p) in &other.val { self.insert(*u, -*p); }
+	}
+}
diff --git a/src/tokens/function.rs b/src/tokens/function.rs
index 28a1bd9..35720c6 100644
--- a/src/tokens/function.rs
+++ b/src/tokens/function.rs
@@ -2,7 +2,6 @@ use std::collections::VecDeque;
 
 use crate::tokens::Token;
 use crate::tokens::Operator;
-use crate::quantity::QuantBase;
 
 #[derive(Debug)]
 #[derive(Copy, Clone)]
diff --git a/src/tokens/operator.rs b/src/tokens/operator.rs
index 700bbe2..13d2de8 100644
--- a/src/tokens/operator.rs
+++ b/src/tokens/operator.rs
@@ -4,7 +4,6 @@ use std::cmp::Ordering;
 use crate::tokens::Token;
 use crate::tokens::Function;
 use crate::quantity::Quantity;
-use crate::quantity::QuantBase;
 
 /// Operator types, in order of increasing priority.
 #[derive(Debug)]