[gov2001-l] Qu2

Jeremy, The issue here is similar to my previous email, but slightly different. The error: always occurs when you use an if(candition) statement, but the condition evaluates to a vector of length k with k>1 (like c(TRUE,FALSE) or so). In this case it is unclear which element R should use (ie. the TRUE or the FALSE) so by default it goes with the first statement and also issues a warning. In this case, the ifelse() command (that triggers a different action depending on element by element checking of the condition) is your best bet to make the function work with vectors. See me previous email and Quan?s on this. Jens From: gov2001-l-bounces at lists.fas.harvard.edu [mailto:gov2001-l-bounces at lists.fas.harvard.edu] On Behalf Of Jeremy Hodgen Sent: Wednesday, February 27, 2008 2:37 AM To: gov2001-l at lists.fas.harvard.edu Subject: Re: [gov2001-l] Qu2 Can anyone help? I'm trying to define the function for qu2 This works fine for individual values of x: g <- function(x){ if ((x < pi/2) & (x > -1*pi/2)) (y <- 10*sin(x)*cos(x)) else (y <- sin(x)*cos(x)) return(y) } But when I input a vector (in order to draw the graph) like this: ruler <- seq(-2*pi, 2*pi, by=.01) g(ruler) I get this error message: Warning message: In if ((x < pi/2) & (x > -1 * pi/2)) (y <- 10 * sin(x) * cos(x)) else (y <- sin(x) * : the condition has length > 1 and only the first element will be used It seems I've got too many conditions for 'if' when the input is a vector. When I draw the graph of g(ruler)~ruler, I get sinxcosx on the domain [-2pi, 2pi]. Any ideas on what I could do differently? Thanks Jeremy Dr Jeremy Hodgen Senior Lecturer in Mathematics Education King's College London Department of Education and Professional Studies Franklin-Wilkins Building Waterloo Bridge Wing 150 Stamford Street London SE1 9NH Tel: 020 7848 3102 Fax: 020 7848 3182 E-mail: jeremy.hodgen at kcl.ac.uk _______________________________________________ gov2001-l mailing list gov2001-l at lists.fas.harvard.edu http://lists.fas.harvard.edu/mailman/listinfo/gov2001-l