Thanks for your posting and using Aspose.Cells.
We have added WEIBULL.DIST in the list of supported functions. Please also see the following document. It enlists all the unsupported function and rest of other functions should be supported.
( http://www.aspose.com/docs/display/cellsnet/Supported+Formula+Functions )
Since WEIBULL.DIST is not in this list, so it is supposed to be among supported functions.
Also you can check any function if it is supported or not using the following code. If the pdf contains error instead of value, then that formula is not supported but if it contains a value, then that formula is supported. I have also attached the source excel file used in this code and the output pdf generated by it for your reference.
String filePath = “F:\Shak-Data-RW\Downloads\Book1.xlsx”;
Workbook workbook = new Workbook(filePath);
workbook.save(filePath + “.out.pdf”);