anchor.diff:  raises_a_number_to_a_power_test_() ->
       [
        ?_assertEqual([32.0], execute ("2 5 **",[])),
  -     assertComplexWithin({-7.461496614688569,2.8854927255134477}, 0.00000001, execute("2 3,4 **",[])),
  -     assertComplexWithin({-37.999999999999986,41.000000000000014}, 0.00000001, execute("3,4 2.5 **",[])),
  -     assertComplexWithin({-14.405859669065997,101.33689785344499}, 0.00000001, execute("1,2 3,-2 **",[]))
  +     assertWithin(9, {-7.461496614688569,2.8854927255134477}, execute("2 3,4 **",[])),
  +     assertWithin(9, {-37.999999999999986,41.000000000000014}, execute("3,4 2.5 **",[])),
  +     assertWithin(9, {-14.405859669065997,101.33689785344499}, execute("1,2 3,-2 **",[]))
       ].
   
   changes_the_sign_of_the_top_number_test_() ->
  
positive.code: 
  % Constants
  knows_the_value_of_pi_test() ->
      assertWithin(3.141592653589793, 0.000000001, execute("pi",[])).
  
  knows_the_value_of_e_test() ->
      assertWithin(2.718281828459045, 0.000000001, execute("e",[])).
  
  knows_the_value_of_phi_test() ->
      assertWithin(1.618033988749895, 0.000000001, execute("phi",[])).
  
  knows_the_value_of_i_test() ->
      ?assertEqual([{0,1}],execute("i",[])).
  
  % Trigonometric
  calculates_sin_of_a_number_in_degrees_test() ->
      assertWithin(0.5, 0.000001, execute("30 sin", [])).
  
  calculates_cos_of_a_number_in_degrees_test() ->
      assertWithin(0.5, 0.000001, execute("60 cos",[])).
  
  calculates_tan_of_a_number_in_degrees_test() ->
      assertWithin(1.0, 0.000001, execute("45 tan",[])).
  
  calculates_asin_of_a_number_in_degrees_test() ->
      assertWithin(30.0, 0.000001, execute("0.5 asin",[])).
  
  calculates_acos_of_a_number_in_degrees_test() ->
      assertWithin(60.0, 0.000001, execute("0.5 acos",[])).
  
  calculates_atan_of_a_number_in_degrees_test() ->
      assertWithin(45.0, 0.000001, execute("1 atan",[])).
  
  % Hyperbolic Trigonometry
  calculates_sinh_of_a_number_test() ->
      assertWithin(3.6268604079, 0.000001, execute("2 sinh", [])).
  
  calculates_cosh_of_a_number_test() ->
      assertWithin(27.30823284, 0.000001, execute("4 cosh",[])).
  
  calculates_tanh_of_a_number_test() ->
      assertWithin(-0.462117157, 0.000001, execute("-0.5 tanh",[])).
  
  calculates_arsinh_of_a_number_test() ->
      assertWithin(2.0, 0.000001, execute("3.6268604079 asinh",[])).
  
  calculates_arcosh_of_a_number_test() ->
      assertWithin(4.0, 0.000001, execute("27.30823284 acosh",[])).
  
  calculates_artanh_of_a_number_test() ->
      assertWithin(-0.5, 0.000001, execute("-0.462117157 atanh",[])).
  
  % Powers and Logarithms
  calculates_the_square_root_of_a_number_test() ->
  
negative.code: 
  parses_a_string_containing_a_complex_number_test_() ->
      lists:map(fun({Input,Expected}) ->
                        assertWithin(9, Expected, execute(Input, []))
                end,
                [ {"5,3", {5,3}},
                  {"-2.0e-3,5", {-0.002,5}},
  