support for NA

[elfunesto]

Thank you very much for this great package. Currently, I have not seen any way to deal with NA and get a "Can not parse NA_real_". It would be great to have a way to deal with this.
Regards

[Marlin-Na]

One way to do it is to convert R's NA to SymEngine's NaN (i.e. S(NaN)). However I think NA and NaN in R have different semantics. NA means missing and does not have a good mapping in SymEngine. I would suggest you convert NA to NaN and then pass it to SymEngine's parser.

[elfunesto]

Thank you for your answer, it fulfils my need!