Casting

class MDArrayTest < Test::Unit::TestCase

context "Arithmetic Tests" do

setup do

  # create a = [20 30 40 50]
  @a = MDArray.arange(20, 60, 10)
  # create b = [0 1 2 3]
  @b = MDArray.arange(4)
  # create c = [1.87 5.34 7.18 8.84]
  @c = MDArray.double([4], [1.87, 5.34, 7.18, 8.84])
  # create d = [[1 2] [3 4]]
  @d = MDArray.int([2, 2], [1, 2, 3, 4])
  # creates an array from a function (actually a block).  The name fromfunction
  # is preserved to maintain API compatibility with NumPy (is it necessary?)
  @e = MDArray.fromfunction("double", [4, 5, 6]) do |x, y, z|
    3.21 * (x + y + z)
  end
  @f = MDArray.fromfunction("double", [4, 5, 6]) do |x, y, z|
    9.57 * x + y + z
  end
  @bool = MDArray.boolean([4], [true, true, false, false])
        
end # setup

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#
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should "do down-casting when in-place operation" do

  # in place operation between an "int" array and a "double" array will keep the 
  # type of a to "int", no up-casting. Values will be truncated
  @a.add! @c
  assert_equal(21, @a[0])
  assert_equal(@a.type, "int")
  
end

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#
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should "do up-casting" do

  # when doing operations between two arrays, the resulting array will have the 
  # highest casting value. result will be of type double
  result = @a + @c
  assert_equal(21.87, result[0])
  assert_equal("double", result.dtype)

end

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#
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should "do up-casting with basic types" do

  result = 1.57 * @a
  # since @a is an int, this should be converted to double, as there is no "float"
  # type in ruby
  assert_equal("double", result.dtype)
  assert_equal(result.to_string, "31.400000000000002 47.1 62.800000000000004 78.5 ")

  result = @c * 1.57
  assert_equal("double", result.dtype)

  # array @a will be cast to "double"
  result = @a ** 2.5
  assert_equal("double", result.dtype)

  # array @c will keep its double type
  result = @c ** 2.5
  assert_equal("double", result.dtype)
  
  # force result to be of given type.  Cannot use binary operators, need to use the
  # corresponding function.  Upcast int @a to float
  result = @a.mul(1.57, "float")
  assert_equal("float", result.dtype)

  result = @a.div(2, "short")
  assert_equal("short", result.dtype)

  # force result to be of given type.  Cannot use binary operators, need to use the
  # corresponding function.
  result = @e.mul(1.57, "float")
  assert_equal("float", result.dtype)


end

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#
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should "allow forced casting" do

  # force result to be of type float, by normal rules it would be of type double
  result = @a.mul(1.57, "float")
  assert_equal("float", result.dtype)
  # final result depends on when casting occurs.  It is possible that the operation
  # is done in double and cast when storing on the float array, or the operation
  # can be done in float already.  Ruby operations perform the former, i.e., 
  # double operation and cast to float.
  if (MDArray.binary_operator == RubyBinaryOperator)
    assert_equal("31.4 47.1 62.8 78.5 ", result.to_string)
  else
    assert_equal("31.400002 47.100002 62.800003 78.5 ", result.to_string)
  end

  # force result to be ot type "int"
  # @a.binary_operator = BinaryOperator
  result = @a.mul(3.43, "int")
  assert_equal(result.type, "int")
  if (MDArray.binary_operator == RubyBinaryOperator)
    # When BinaryOperator with force casting, values are operated first and then
    # casted.  So, in the example above we have 20 * 3.43 = 68,6 and then the value
    # is casted to int for a result of 68
    assert_equal(68, result[0])
  else
    # When we cast earlier values are first cast to the the selected type
    # and then operated upon.  So, in the example we have 20 * 3.43, which becomes
    # 20 * 3 = 60
    assert_equal(60, result[0])
  end

end

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#
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should "allow mixing types" do

  # adding double to number
  res = @c + 10.5
  assert_equal(res.to_string, "12.370000000000001 15.84 17.68 19.34 ")
  # adding two double arrays
  res = @e + @f

  # adding a double to an int, should cast to double
  res = @c + @a
  assert_equal("21.87 35.34 47.18 58.84 ", res.to_string)
  # adding an int to a double, should cast to double
  res = @a + @c
  assert_equal("21.87 35.34 47.18 58.84 ", res.to_string)
  # adding an int array to a (ruby) float/double number, should cast to double
  res = @a + 10.55
  assert_equal("30.55 40.55 50.55 60.55 ", res.to_string)
  # adding two ints
  res = @a + @b
  assert_equal(res.to_string, "20 31 42 53 ")
  # unary operation on arrays
  res = @c.floor
  assert_equal(res.to_string, "1.0 5.0 7.0 8.0 ")
  # Can also operate with the number first.  Still doing elementwise operation
  c = 10 / @c
  assert_equal("5.347593582887701 1.8726591760299627 1.392757660167131 1.1312217194570136 ",
               c.to_string)

end

end

end