Wrong cell code was formed by copying parts of expressions (copied expression was using EngeneeringForm). Displayed expression was correct, but output was completely wrong.
My question is: How could I know it was a wrong result ? If I share my cell data, how can others know the expression is corrupted ? Can we trust what Mathematica displays in notebook expressions ?
Similar problems, both flagged as bugs and corrected: https://mathematica.stackexchange.com/q/114949/74135 : Why a function returns two different values if copied into a Notebook or imported with Get from a Wolfram Mathematica Package? (no error indication) and https://mathematica.stackexchange.com/q/982/74135 : How to find pieces of code responsible for syntax errors? (here a syntax error was indicated, but the Boxes problem seems to be quite similar).
Problem Details:
The low-level error is due to hidden parenthesis that only shows up in a latex “copy as” output:
i 120 \pi \left(\frac{28.15}{10^6}+\frac{1}{\frac{i 120 \pi 10}{10^3}}+\frac{1}{50}\right)
The displayed (and correct) expression have no parenthesis:
i 120 \pi 28.15 \times 10^{-6}+\frac{1}{\displaystyle i 120 \pi 10\times 10^{-3}}+\frac{1}{50}
Problem lies on inconsistent (pasted) boxes expression :
Cell[BoxData[
RowBox[{"\[ImaginaryJ]", " ", "120", " ", "\[Pi]",
TagBox[
RowBox[{
RowBox[{"(",
RowBox[{"28.1448", " ",
SuperscriptBox["10",
RowBox[{"-", "6"}]]}], ")"}], "+",
FractionBox[
StyleBox["1",
ShowStringCharacters->False],
RowBox[{"\[ImaginaryJ]", " ", "120", " ", "\[Pi]", " ", "10", " ",
SuperscriptBox["10",
RowBox[{"-", "3"}]]}]], "+",
FractionBox["1", "50"]}],
EngineeringForm]}]], "Input"
Correct boxes expression:
Cell[BoxData[
RowBox[{
RowBox[{"\[ImaginaryJ]", " ", "120", "\[Pi]", " ", "28.15", " ",
SuperscriptBox["10",
RowBox[{"-", "6"}]]}], "+",
SuperscriptBox[
RowBox[{"(",
RowBox[{"\[ImaginaryJ]", " ", "120", "\[Pi]", " ", "10", " ",
SuperscriptBox["10",
RowBox[{"-", "3"}]]}], ")"}],
RowBox[{"-", "1"}]], "+",
FractionBox["1", "50"]}]], "Input"]
Thanks!