Merge pull request #29 from ApproxFun/master

Add support for Dual{Complex}

.travis.yml

@@ -1,9 +1,9 @@
+# Documentation: http://docs.travis-ci.com/user/languages/julia/
 language: julia
 os:
   - linux
   - osx
 julia:
-  - 0.3
   - 0.4
   - nightly
 notifications:

README.md

@@ -2,22 +2,23 @@
 
 ### Scope of DualNumbers.jl
 
-The `DualNumbers` package defines the `Dual` type to represent dual numbers and 
-supports standard mathematical operations on them. Conversions and promotions 
-are defined to allow performing operations on combinations of dual numbers with 
+The `DualNumbers` package defines the `Dual` type to represent dual numbers and
+supports standard mathematical operations on them. Conversions and promotions
+are defined to allow performing operations on combinations of dual numbers with
 predefined Julia numeric types.
 
-Dual numbers extend the real numbers, similar to complex numbers. They adjoin a 
-new element `ϵ` such that `ϵ*ϵ=0`, in a similar way that complex numbers 
-adjoin the imaginary unit `i` with the property `i*i=-1`. So the typical 
-representation of a dual number takes the form `x+y*ϵ`, where `x` and `y` are 
-real numbers.
-
-Apart from their mathematical role in algebraic and differential geometry (they 
-are mainly interpreted as angles between lines), they also find applications in 
-physics (the real part of a dual represents the bosonic direction, while the 
-epsilon part represents the fermionic direction), in screw theory, in motor 
-and spatial vector algebra, and in computer science due to its relation with the 
+Dual numbers extend the real numbers, similar to complex numbers. They adjoin a
+new element `ɛ` such that `ɛ*ɛ=0`, in a similar way that complex numbers
+adjoin the imaginary unit `i` with the property `i*i=-1`. So the typical
+representation of a dual number takes the form `x+y*ɛ`, where `x` and `y` are
+real numbers. Duality can further extend complex numbers by adjoining one new
+element to each of the real and imaginary parts.
+
+Apart from their mathematical role in algebraic and differential geometry (they
+are mainly interpreted as angles between lines), they also find applications in
+physics (the real part of a dual represents the bosonic direction, while the
+epsilon part represents the fermionic direction), in screw theory, in motor
+and spatial vector algebra, and in computer science due to its relation with the
 forward mode of automatic differentiation.
 
 The [ForwardDiff](https://github.com/scidom/ForwardDiff.jl) package implements forward mode automatic differentiation in Julia using several approaches. One
@@ -27,65 +28,71 @@ dual numbers in Julia.
 
 ## Supported functions
 
-We aim for complete support for `Dual` types for numerical functions within Julia's 
+We aim for complete support for `Dual` types for numerical functions within Julia's
 `Base`. Currently, basic mathematical operations and trigonometric functions are
 supported.
 
 
 The following functions are specific to dual numbers:
 * `dual`,
-* `dual128`,
-* `dual64`,
+* `realpart`,
+* `dualpart`,
 * `epsilon`,
 * `isdual`,
 * `dual_show`,
 * `conjdual`,
 * `absdual`,
 * `abs2dual`.
 
-In some cases the mathematical definition of functions of ``Dual`` numbers
-is in conflict with their use as a drop-in replacement for calculating
-numerical derivatives, for example, ``conj``, ``abs`` and ``abs2``. In these
-cases, we choose to follow the rule ``f(x::Dual) = Dual(f(real(x)),epsilon(x)*f'(real(x)))``,
-where ``f'`` is the derivative of ``f``. The mathematical definitions are
-available using the functions with the suffix ``dual``.
-Similarly, comparison operators ``<``, ``>``, and ``==`` are overloaded to compare only real
-components.
+The dual number `f(a+bɛ)` is defined by the limit:
 
+    f(a+bɛ) := f(a) + lim_{h→0} (f(a + bɛh) - f(a))/h .
 
+For complex differentiable functions, this is equivalent to differentiation:
 
+    f(a+bɛ) := f(a) + b f'(a) ɛ.
+
+For functions that are not complex differentiable, the dual part returns the limit
+and can be identified with a directional derivative in `R²`.
+
+In some cases the mathematical definition of functions of ``Dual`` numbers
+is in conflict with their use as a drop-in replacement for calculating
+numerical derivatives, for example, ``conj``, ``abs`` and ``abs2``. The mathematical
+definitions are available using the functions with the suffix ``dual``.
+Similarly, comparison operators ``<``, ``>``, and ``==`` are overloaded to compare only value
+components.
 
 ### A walk-through example
 
-The example below demonstrates basic usage of dual numbers by employing them to 
-perform automatic differentiation. The code for this example can be found in 
+The example below demonstrates basic usage of dual numbers by employing them to
+perform automatic differentiation. The code for this example can be found in
 `test/automatic_differentiation_test.jl`.
 
 First install the package by using the Julia package manager:
 
     Pkg.update()
     Pkg.add("DualNumbers")
-    
+
 Then make the package available via
 
     using DualNumbers
 
-Use the `dual()` function to define the dual number `2+1*du`:
+Use the `Dual()` constructor to define the dual number `2+1*ɛ`:
 
-    x = dual(2, 1)
+    x = Dual(2, 1)
 
 Define a function that will be differentiated, say
 
     f(x) = x^3
 
-Perform automatic differentiation by passing the dual number `x` as argument to 
+Perform automatic differentiation by passing the dual number `x` as argument to
 `f`:
 
     y = f(x)
 
-Use the functions `real()` and `epsilon()` to get the real and imaginary (dual) 
+Use the functions `realpart` and `dualpart` to get the concrete and dual
 parts of `x`, respectively:
 
     println("f(x) = x^3")
-    println("f(2) = ", real(y))
-    println("f'(2) = ", epsilon(y))
+    println("f(2) = ", realpart(y))
+    println("f'(2) = ", dualpart(y))

REQUIRE

@@ -1,4 +1,3 @@
-julia 0.3
+julia 0.4
 Calculus
 NaNMath
-Compat

src/DualNumbers.jl

@@ -1,28 +1,36 @@
-isdefined(Base, :__precompile__) && __precompile__()
+__precompile__()
 
 module DualNumbers
   importall Base
 
-  using Compat
   import NaNMath
   import Calculus
 
   include("dual.jl")
   include("dual_n.jl")
 
+  Base.@deprecate_binding du ɛ
+  @deprecate inf{T}(::Type{Dual{T}}) convert(Dual{T}, Inf)
+  @deprecate nan{T}(::Type{Dual{T}}) convert(Dual{T}, NaN)
+  @deprecate real{T<:Real}(z::Dual{T}) realpart(z)
+
   export
     Dual,
     Dual128,
     Dual64,
-    DualPair,
+    Dual32,
+    DualComplex256,
+    DualComplex128,
+    DualComplex64,
     dual,
-    dual128,
-    dual64,
+    epsilon,
+    realpart,
+    dualpart,
     isdual,
     dual_show,
-    epsilon,
     conjdual,
     absdual,
     abs2dual,
-    du
+    ɛ,
+    imɛ
 end