"Paul Smith" <[EMAIL PROTECTED]> writes: > Thanks, Peter. I did not know about the existence of the command > 'eval', in spite of the fact of having searched the Internet for a > solution for my problem. > > 'eval' seems not working in connection with Ryacas: > > > library(Ryacas) > > x <- yacas("2/3*5/7") > > x > expression(10/21) > > eval(x) > expression(10/21) > > > > To work, one has to do the following: > > eval(x) > expression(10/21) > > eval(as.expression(x)) > [1] 0.4761905
This could be the following effect in action: > quote(expression(10/21)) expression(10/21) > eval(quote(expression(10/21))) expression(10/21) > eval(eval(quote(expression(10/21)))) [1] 0.4761905 which is one of the weirder anomalies in the parse/deparse area in the R language. Part of the secret is > quote(expression(10/21)) expression(10/21) > mode(quote(expression(10/21))) [1] "call" > mode(expression(10/21)) [1] "expression" and you might look at mode(x) to see whether this is relevant to Ryacas. -- O__ ---- Peter Dalgaard Ă˜ster Farimagsgade 5, Entr.B c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.