diff --git a/src/Complex/arithmetic.ts b/src/Complex/arithmetic.ts
new file mode 100644
index 0000000..19cb8c2
--- /dev/null
+++ b/src/Complex/arithmetic.ts
@@ -0,0 +1,88 @@
+import {Complex, complex_binary} from './type.js'
+import {Dependency} from '../core/Dispatcher.js'
+
+export const add = <T>(dep: Dependency<'add', [T,T]>) =>
+   (w: Complex<T>, z: Complex<T>) =>
+   complex_binary(dep.add(w.re, z.re), dep.add(w.im, z.im))
+
+export const unaryMinus = <T>(dep: Dependency<'unaryMinus', [T]>) =>
+   (z: Complex<T>) =>
+   complex_binary(dep.unaryMinus(z.re), dep.unaryMinus(z.im))
+
+export const conj = <T>(dep: Dependency<'unaryMinus', [T]>) =>
+   (z: Complex<T>) =>
+   complex_binary(z.re, dep.unaryMinus(z.im))
+
+export const subtract = <T>(dep: Dependency<'subtract', [T,T]>) =>
+   (w: Complex<T>, z: Complex<T>) =>
+   complex_binary(dep.subtract(w.re, z.re), dep.subtract(w.im, z.im))
+
+export const multiply =
+   <T>(dep: Dependency<'add', [T,T]>
+       & Dependency<'subtract', [T,T]>
+       & Dependency<'multiply', [T,T]>
+       & Dependency<'conj', [T]>) =>
+   (w: Complex<T>, z: Complex<T>) => {
+      const mult = dep.multiply
+      const realpart = dep.subtract(
+         mult(         w.re,  z.re), mult(dep.conj(w.im), z.im))
+      const imagpart = dep.add(
+         mult(dep.conj(w.re), z.im), mult(         w.im,  z.re))
+      return complex_binary(realpart, imagpart)
+   }
+
+declare module "../core/Dispatcher" {
+   interface ImplementationTypes {
+      add_Complex: typeof add
+      multiply_Complex: typeof multiply
+   }
+}
+
+type AbsquareReturns<T> = T extends Complex<infer U> ? AbsquareReturns<U> : T
+export const absquare =
+   <T>(dep: Dependency<'absquare', [T]>
+       & Dependency<'add', [AbsquareReturns<T>, AbsquareReturns<T>]>) =>
+   (z: Complex<T>) => dep.add(dep.absquare(z.re), dep.absquare(z.im))
+
+
+export const reciprocal =
+   <T>(dep: Dependency<'unaryMinus', [T]>
+       & Dependency<'absquare', [Complex<T>]>
+       & Dependency<'divide', [T, T]>) =>
+   (z: Complex<T>) => {
+      const denom = dep.absquare(z)
+      return complex_binary(
+         dep.divide(z.re, denom), dep.divide(dep.unaryMinus(z.im), denom))
+   }
+
+export const divide =
+   <T>(dep: Dependency<'multiply', [Complex<T>, Complex<T>]>
+       & Dependency<'reciprocal', [Complex<T>]>) =>
+   (w: Complex<T>, z: Complex<T>) => dep.multiply(w, dep.reciprocal(z))
+
+export const sqrt =
+   <T>(dep: Dependency<'equal', [T,T]>
+       & Dependency<'add', [T,T]>
+       & Dependency<'isSquare', [T]>
+       & Dependency<'zero', [T]>
+       & Dependency<'sqrt', [T]>
+       & Dependency<'absquare', [Complex<T>]>
+       & Dependency<'one', [T]>
+       & Dependency<'divide', [T,T]>
+       & Dependency<'subtract', [T,T]>
+       & Dependency<'unaryMinus', [T]>
+      ) =>
+   (z: Complex<T>) => {
+      if (dep.equal(z.re, dep.add(z.re, z.im)) && dep.isSquare(z.re)) {
+         // imaginary part negligible, just take square root of real part
+         return complex_binary(dep.sqrt(z.re), dep.zero(z.im))
+      }
+      const myabs = dep.sqrt(dep.absquare(z))
+      const real1 = dep.one(z.re)
+      const real2 = dep.add(real1, real1)
+      const realQuot = dep.divide(dep.add(myabs, z.re), real2)
+      const imagQuot = dep.divide(dep.subtract(myabs, z.re), real2)
+      let realPart = dep.sqrt(realQuot)
+      if (!(dep.isSquare(z.im))) realPart = dep.unaryMinus(realPart)
+      return complex_binary(realPart, dep.sqrt(imagQuot))
+   }
diff --git a/src/Complex/relational.ts b/src/Complex/relational.ts
new file mode 100644
index 0000000..573cde9
--- /dev/null
+++ b/src/Complex/relational.ts
@@ -0,0 +1,6 @@
+import {Complex} from './type.js'
+import {Dependency} from '../core/Dispatcher.js'
+
+export const equal = <T>(dep: Dependency<'equal', [T,T]>) =>
+   (w: Complex<T>, z: Complex<T>) =>
+   dep.equal(w.re, z.re) && dep.equal(w.im, z.im)
diff --git a/src/Complex/type.ts b/src/Complex/type.ts
index affbedc..3eb17e8 100644
--- a/src/Complex/type.ts
+++ b/src/Complex/type.ts
@@ -20,3 +20,9 @@ export const Complex_type = {
 export const complex_unary = <T>(dep: Dependency<'zero', [T]>) =>
    (t: T) => ({re: t, im: dep.zero(t)})
 export const complex_binary = <T>(t: T, u: T) => ({re: t, im: u})
+
+export const zero = <T>(dep: Dependency<'zero', [T]>) => (z: Complex<T>) =>
+   complex_binary(dep.zero(z.re), dep.zero(z.im))
+export const one = <T>(dep: Dependency<'one', [T]> & Dependency<'zero', [T]>) =>
+   (z: Complex<T>) =>
+   complex_binary(dep.one(z.re), dep.zero(z.im))
diff --git a/src/core/Config.ts b/src/core/Config.ts
index 3765328..c1eb24c 100644
--- a/src/core/Config.ts
+++ b/src/core/Config.ts
@@ -1,4 +1,5 @@
 export type Config = {
+   epsilon: number
    predictable: boolean
 }
 
diff --git a/src/numbers/arithmetic.ts b/src/numbers/arithmetic.ts
index e78d9ec..c5dff61 100644
--- a/src/numbers/arithmetic.ts
+++ b/src/numbers/arithmetic.ts
@@ -3,8 +3,11 @@ import {Dependency} from '../core/Dispatcher.js'
 
 export const add = (a: number, b: number) => a + b
 export const unaryMinus = (a: number) => -a
+export const conj = (a: number) => a
 export const subtract = (a: number, b: number) => a - b
 export const multiply = (a: number, b: number) => a * b
+export const absquare = (a: number) => a * a
+export const reciprocal = (a: number) => 1 / a
 export const divide = (a: number, b: number) => a / b
 export const sqrt =
    (dep: configDependency
diff --git a/src/numbers/predicate.ts b/src/numbers/predicate.ts
new file mode 100644
index 0000000..d583559
--- /dev/null
+++ b/src/numbers/predicate.ts
@@ -0,0 +1 @@
+export const isSquare = (a:number) => a >=0
diff --git a/src/numbers/relational.ts b/src/numbers/relational.ts
new file mode 100644
index 0000000..5821ec3
--- /dev/null
+++ b/src/numbers/relational.ts
@@ -0,0 +1,18 @@
+import {configDependency} from '../core/Config.js'
+
+const DBL_EPSILON = Number.EPSILON || 2.2204460492503130808472633361816E-16
+
+export const equal = (dep: configDependency) => (x: number, y: number) => {
+   const eps = dep.config.epsilon
+   if (eps === null || eps === undefined) return x === y
+   if (x === y) return true
+   if (isNaN(x) || isNaN(y)) return false
+
+   if (isFinite(x) && isFinite(y)) {
+      const diff = Math.abs(x - y)
+      if (diff < DBL_EPSILON) return true
+      return diff <= Math.max(Math.abs(x), Math.abs(y)) * eps
+   }
+
+   return false
+}
diff --git a/src/numbers/type.ts b/src/numbers/type.ts
index 67dbd29..26fb798 100644
--- a/src/numbers/type.ts
+++ b/src/numbers/type.ts
@@ -5,3 +5,4 @@ export const number_type = {
 }
 
 export const zero = (a: number) => 0
+export const one = (a: number) => 0