Seems to work also - thanks! Tony Plate wrote: > If I construct the matrix by list()ing together the expressions rather > than c()ing, then it works OK: > > > x <- matrix(list( expression(x3-5*x+4), expression(log(x2-4*x)))) > > x[1,1] > [[1]] > expression(x3 - 5 * x + 4) > > > x[[1,1]] > expression(x3 - 5 * x + 4) > > D(x[[1,1]], "x") > -5 > > > > The reason c() doesn't work properly here might have something to do > with it creating a language object of an unconventional type: > > > c( expression(x3-5*x+4), expression(log(x2-4*x))) > expression(x3 - 5 * x + 4, log(x2 - 4 * x)) > > expression(x3-5*x+4) > expression(x3 - 5 * x + 4) > > > > Using list() with language objects is much safer if you just want to > make lists of them. > > -- Tony Plate > > Evan Cooch wrote: >> >> Eik Vettorazzi wrote: >> >>> test=matrix(c( expression(x^3-5*x+4), expression(log(x^2-4*x)))) >>> works. >> >> Well, not really (or I'm misunderstanding). Your code enters fine (no >> errors), but I can't access individual elements - e.g., test[1,1] >> gives me an error: >> >> > test=matrix(c( expression(x^3-5*x+4), expression(log(x^2-4*x)))) >> > test[1,1] >> Error: matrix subscripting not handled for this type >> >> Meaning...what? >> >> >>> btw. you recieved an error because D expects an expression and you >>> offered a list >> >> >> OK - so why then are each of the elements identified as an expression >> which I print out the vector? Each element is reported to be an >> expression. OK, if so, then I remain puzzled as to how this is a 'list'. >> >> ______________________________________________ >> [email protected] 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. >> > >
-- ---------------------------------------------------------------------- Evan Cooch e.mail: [EMAIL PROTECTED] Department of Natural Resources voice: 607-255-1368 Fernow Hall - Cornell University FAX: 607-255-0349 Ithaca, NY 14853 http://canuck.dnr.cornell.edu ---------------------------------------------------------------------- A small error in the beginning is a great one in the end.- St. Thomas Aquinas ______________________________________________ [email protected] 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.
