Re: [R] Computational problems in R

2008-10-28 Thread Steven McKinney
bin Hankin [mailto:[EMAIL PROTECTED] Sent: Tue 10/28/2008 12:58 AM To: A.Noufaily Cc: Duncan Murdoch; r-help@r-project.org; [EMAIL PROTECTED]; Steven McKinney; Xiaoxu LI Subject: Re: [R] Computational problems in R Hello. The Brobdingnag package uses that identity for a logarithmic representati

Re: [R] Computational problems in R

2008-10-28 Thread Robin Hankin
AIL PROTECTED] Sent: Saturday, October 25, 2008 11:36 AM To: Steven McKinney Cc: A.Noufaily; r-help@r-project.org Subject: Re: [R] Computational problems in R On 24/10/2008 9:50 PM, Steven McKinney wrote: I suspect there's a deeper issue here. sum(exp(yi)) when large yi occur is problematic.

Re: [R] Computational problems in R

2008-10-27 Thread A.Noufaily
. However, I might still use logs in case (1 + B/A)>0. Regards, Amy -Original Message- From: Duncan Murdoch [mailto:[EMAIL PROTECTED] Sent: Saturday, October 25, 2008 11:36 AM To: Steven McKinney Cc: A.Noufaily; r-help@r-project.org Subject: Re: [R] Computational problems in R On 24

Re: [R] Computational problems in R

2008-10-25 Thread Duncan Murdoch
at+ bccrc +dot+ ca tel: 604-675-8000 x7561 BCCRC Molecular Oncology 675 West 10th Ave, Floor 4 Vancouver B.C. V5Z 1L3 Canada -Original Message- From: [EMAIL PROTECTED] on behalf of Duncan Murdoch Sent: Fri 10/24/2008 4:04 PM To: A.Noufaily Cc: r-help@r-project.org Subject: Re: [R] Comp

Re: [R] Computational problems in R

2008-10-24 Thread Steven McKinney
10th Ave, Floor 4 Vancouver B.C. V5Z 1L3 Canada -Original Message- From: [EMAIL PROTECTED] on behalf of Duncan Murdoch Sent: Fri 10/24/2008 4:04 PM To: A.Noufaily Cc: r-help@r-project.org Subject: Re: [R] Computational problems in R On 24/10/2008 12:42 PM, A.Noufaily wrote: > Dear a

Re: [R] Computational problems in R

2008-10-24 Thread Duncan Murdoch
On 24/10/2008 12:42 PM, A.Noufaily wrote: Dear all, I would be grateful if anyone can help me with the following: My aim is to compute explicitely the sum S=A+B where A=sum(exp(c_i/d)), i=1,...,n; B, c_i, and d are real numbers with -Inf0. The problem is that when c_i/d >710 (for some i) R is s

Re: [R] Computational problems in R

2008-10-24 Thread Xiaoxu LI
I think you should try one X for A/X=sum(exp(c_i/d -log(X))) The optional X could be as the following ... ## to test ### C = c(c_i/d; i=1,2,...,n) n<-1000; C<-runif(n,700,1000); # M<-1;while (2*M < Inf) M<-2*M; X<- exp(max(C) - log (M/n)); cat('A=',sum(exp(C-log(X))),'*',X)

[R] Computational problems in R

2008-10-24 Thread A.Noufaily
Dear all, I would be grateful if anyone can help me with the following: My aim is to compute explicitely the sum S=A+B where A=sum(exp(c_i/d)), i=1,...,n; B, c_i, and d are real numbers with -Inf0. The problem is that when c_i/d >710 (for some i) R is setting exp(c_i/d) to be equal to +Inf and h