Hi Tom,
Sorry for the delay in responding. XlsIO formula parser can parse next unary expression. Use the following code snippet to parse unary expression.
[C#]
// Unary expression.
sheet.Range["B1"].Formula="+++1";
sheet.Range["B2"].Formula="+-+1";
Here is a sample for your reference:
FormulaParser.zip
Please take a look at the sample above and let me know if you have any questions.
Regards,
Melba