Some remarks: Why are you using assignments to indicate the return values of functions? This is R idiom: > f<-function(u){ > f<-0 > for (j in 1:4){ > f<-f+coeff[j]*(zeta(j)(u)) > } > f > } >
If you only want the inner product of 2 vector, "outer" probably is an overkill. g <- function(u){ sum(coeff * zeta(1:4)(u)) } should be enough. And plot(g) does not work because g is not vectorized. plot(Vectorize(g)) will work On Nov 16, 2010, at 1:18 AM, Eduardo de Oliveira Horta wrote: > Hello, > > I was trying to build some functions which I would like to integrate over an > interval using the function 'integrate' from the 'stats' package. As an > example, please consider the function > > h(u)=sin(pi*u) + sqrt(2)*sin(pi*2*u) + sqrt(3)*sin(pi*3*u) + 2*sin(pi*4*u) > > Two alternative ways to 'build' this function are as in f and g below: > > coeff<-sqrt(1:4) > > zeta<-function(i) {force(i); function(u){ > zeta<-sqrt(2)+sin(pi*i*u) > }} > > f<-function(u){ > f<-0 > for (j in 1:4){ > f<-f+coeff[j]*(zeta(j)(u)) > } > f<-f > } > > g<-function(u){ > g<-crossprod(coeff,zeta(1:4)(u)) > } > > Obviously, f and g are equivalent, but in the actual code I am writing, g is > much faster. However, I can't seem to integrate (neither to plot) g. In > fact, these are the error messages I get: > >> print(f(.1)) > [1] 4.443642 >> print(g(.1)) > [,1] > [1,] 4.443642 > > Everything ok until here... but... > > When using plot(), I get this: > >> plot(f) #plots, as expected. >> plot(g) > Error in crossprod(coeff,zeta(1:4)(u)) : arguments not compatible > Besides that: Warning message: > In pi * i * u : > longer object length is not a multiple of shorter object length > > When using integrate(), I get this: > >> integrate(f,0,1) > 1.004172 with absolute error < 2.5e-13 >> integrate(g,0,1) > Error in crossprod(coeff,zeta(1:4)(u)) : arguments not compatible > Besides that: Warning message: > In pi * i * u : > longer object length is not a multiple of shorter object length >> > > I have already tried some simple 'solutions', for example to set > g<-function(u){ > vec1<-drop(coeff) > vec2<-drop(zeta(1:4)(u)) > g<-drop(crossprod(coeff,zeta(1:4)(u))) > } > > as well as using the %*% operation, but these won't solve my problem. > > Any suggestions would be welcome. Thanks in advance, > > Eduardo Horta > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org 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. > -- Erich Neuwirth, University of Vienna Faculty of Computer Science Center for Computer Science Didactics and Learning Research Visit our SunSITE at http://sunsite.univie.ac.at Phone: +43-1-4277-39902 Fax: +43-1-4277-39459 ______________________________________________ R-help@r-project.org 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.