Return special floats as atoms, not nils

versilov · May 13, 2018 · 5c19608 · 5c19608
1 parent fe72276
commit 5c19608
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Showing 2 changed files with 18 additions and 23 deletions.
diff --git a/lib/matrex.ex b/lib/matrex.ex
@@ -43,7 +43,7 @@ defmodule Matrex do
   ## NaN and Infinity
 
   Float special values, like `NaN` and `Inf` live well inside matrices.
-  But when getting them into Elixir they are transferred to `nil` values,
+  But when getting them into Elixir they are transferred to `Nan`,`Inf` and `NegInf` atoms,
   because BEAM does not accept special values as valid floats.
 
       iex> m = Matrex.eye(3)
@@ -54,14 +54,20 @@ defmodule Matrex do
       │     0.0     0.0     1.0 │
       └                         ┘
 
-      iex> Matrex.divide(m, Matrex.zeros(3))
+      iex> n = Matrex.divide(m, Matrex.zeros(3))
       #Matrex[3×3]
       ┌                         ┐
       │       ∞     NaN     NaN │
       │     NaN       ∞     NaN │
       │     NaN     NaN       ∞ │
       └                         ┘
 
+      iex> n[1][1]
+      Inf
+
+      iex> n[1][2]
+      NaN
+
   """
 
   alias Matrex.NIFs
@@ -597,9 +603,9 @@ defmodule Matrex do
   end
 
   @spec binary_to_float(<<_::32>>) :: element | nil
-  defp binary_to_float(@not_a_number), do: nil
-  defp binary_to_float(@positive_infinity), do: nil
-  defp binary_to_float(@negative_infinity), do: nil
+  defp binary_to_float(@not_a_number), do: NaN
+  defp binary_to_float(@positive_infinity), do: Inf
+  defp binary_to_float(@negative_infinity), do: NegInf
   defp binary_to_float(<<val::float-little-32>>), do: val
 
   @doc """
@@ -851,27 +857,16 @@ defmodule Matrex do
       6.0
 
   """
-  @spec first(matrex) :: element | nil
-  def first(%Matrex{
-        data: <<
-          _rows::unsigned-integer-little-32,
-          _columns::unsigned-integer-little-32,
-          specl_float::binary-size(4),
-          _rest::binary
-        >>
-      })
-      when specl_float in [@not_a_number, @positive_infinity, @negative_infinity],
-      do: nil
-
+  @spec first(matrex) :: element | NaN | Inf | NegInf
   def first(%Matrex{
         data: <<
           _rows::unsigned-integer-little-32,
           _columns::unsigned-integer-little-32,
-          element::float-little-32,
+          element::binary-4,
           _rest::binary
         >>
       }),
-      do: element
+      do: binary_to_float(element)
 
   @doc """
   Displays a visualization of the matrix.

diff --git a/lib/matrex/inspect.ex b/lib/matrex/inspect.ex
@@ -101,7 +101,7 @@ defmodule Matrex.Inspect do
   defp format_row(%Matrex{} = matrex, row, _rows, columns, suffix_size, prefix_size)
        when suffix_size + prefix_size >= columns do
     matrex
-    |> Matrex.row_to_list(row)
+    |> row_to_list_of_binaries(row)
     |> Enum.map(&format_float(&1))
     |> Enum.join()
   end
@@ -136,13 +136,13 @@ defmodule Matrex.Inspect do
 
   defp format_row_head_tail(<<>>, _, _), do: <<>>
 
-  defp format_row_head_tail(<<val::float-little-32, rest::binary>>, 1, prefix_size)
+  defp format_row_head_tail(<<val::binary-4, rest::binary>>, 1, prefix_size)
        when prefix_size > 0 do
     <<format_float(val) <> IO.ANSI.white() <> " │\n│" <> IO.ANSI.yellow(),
       format_row_head_tail(rest, 0, prefix_size)::binary>>
   end
 
-  defp format_row_head_tail(<<val::float-little-32, rest::binary>>, 0, prefix_size)
+  defp format_row_head_tail(<<val::binary-4, rest::binary>>, 0, prefix_size)
        when prefix_size > 0 do
     <<
       format_float(val)::binary,
@@ -151,7 +151,7 @@ defmodule Matrex.Inspect do
     >>
   end
 
-  defp format_row_head_tail(<<val::float-little-32, rest::binary>>, suffix_size, prefix_size)
+  defp format_row_head_tail(<<val::binary-4, rest::binary>>, suffix_size, prefix_size)
        when suffix_size > 0 do
     <<format_float(val)::binary,
       format_row_head_tail(rest, suffix_size - 1, prefix_size)::binary>>