Changing the API around

.gitignore

@@ -1,4 +1,3 @@
-/docs/
 /lib/
 /bin/
 /.shards/

src/apatite/linear_algebra.cr

@@ -0,0 +1,27 @@
+require "./linear_algebra/ndarray"
+require "./linear_algebra/matrix"
+require "./linear_algebra/vector"
+
+module Apatite
+  module LinearAlgebra
+    extend self
+
+    # Calculates the sigmoid curve for a numeric input.
+    #
+    # f(x) = 1/(1 + e^-x)
+    #
+    # See also: [Sigmoid function [WikiWand]](https://www.wikiwand.com/en/Sigmoid_function)
+    def sigmoid(input : Number)
+      num = input.to_f64
+      1 / (1 + Math.exp(-num))
+    end
+
+    # Calculates the derivative sigmoid curve for a numeric input.
+    #
+    # f'(x) = f(x)(1 - f(x)),
+    def sigmoid_d(input : Number)
+      num = input.to_f64
+      num * (1 - num)
+    end
+  end
+end

src/apatite/linear_algebra/matrix.cr

@@ -1,6 +1,6 @@
 require "./vector"
 
-module Apatite
+module Apatite::LinearAlgebra
   class Matrix
     include Enumerable(Vector)
     include Indexable(Vector)

src/apatite/linear_algebra/ndarray.cr

@@ -1,4 +1,4 @@
-module Apatite
+module Apatite::LinearAlgebra
   class NDArray
     include Enumerable(Float64)
     include Indexable(Float64)

src/apatite/linear_algebra/vector.cr

@@ -1,6 +1,4 @@
-require "../../apatite"
-
-module Apatite
+module Apatite::LinearAlgebra
   # Represents a mathematical vector, and also constitutes a row or column
   # of a `Matrix`
   class Vector
@@ -8,8 +6,13 @@ module Apatite
     include Indexable(Float64)
     include Comparable(Vector)
 
+    # Cartesian unit vector I
     I = Vector.create([1.0, 0.0, 0.0])
+
+    # Cartesian unit vector J
     J = Vector.create([0.0, 1.0, 0.0])
+
+    # Cartesian unit vector K
     K = Vector.create([0.0, 0.0, 1.0])
 
     @buffer : Pointer(Float64)
@@ -386,8 +389,6 @@ module Apatite
       Matrix[*vs].rank.equal?(vs.count)
     end
 
-
-
     # Invokes the given block for each element of `self`, replacing the element
     # with the value returned by the block. Returns `self`.
     #
@@ -701,6 +702,12 @@ module Apatite
       map_with_index { |x, i| q[i - 1] + (q[i - 1] - x) }
     end
 
+    # Sums the numbers in the vector and returns a sigmoid value
+    # across the whole vector.
+    def sigmoid
+      LinearAlgebra.sigmoid(sum)
+    end
+
     # Utility to make sure vectors are 3D. If they are 2D, a zero
     # z-component is added.
     def to_3d
@@ -782,7 +789,6 @@ module Apatite
       all?(&.zero?)
     end
 
-    # :nodoc:
     protected def size=(size : Int)
       @size = size.to_i
     end

src/apatite/version.cr

@@ -0,0 +1,3 @@
+module Apatite
+  VERSION = "0.1.0"
+end