Displaying 20 results from an estimated 900 matches similar to: "how to compute this summation..."
2008 Aug 29
1
more efficient double summation...
Dear R users...
I made the R-code for this double summation computation
http://www.nabble.com/file/p19213599/doublesum.jpg
-------------------------------------------------
Here is my code..
sum(sapply(1:m, function(k){sum(sapply(1:m,
function(j){x[k]*x[j]*dnorm((mu[j]+mu[k])/sqrt(sig[k]+sig[j]))/sqrt(sig[k]+sig[j])}))}))
-------------------------------------------------
In fact, this is
2008 Nov 15
1
make a triple summation more efficient
Dear R users...
I made the R-code for this triple summation computation
http://www.nabble.com/file/p20517134/a.jpg
-------------------------------------------------
Here is my code..
x=seq(.1,1,.1); l=10
y=seq(1,10); m=10
z=seq(.1,1,.1); n=10
sum(sapply(1:l, function(i) {sum(sapply(1:m, function(j) {sum(sapply(1:n,
function(k){exp(x[i]*y[j]*z[k] )/gamma(y[j]+1)}))^(1.5) }))}))
2009 May 01
2
Double summation limits
Dear R experts
I need to write a function that incorporates double summation, the problem
being that the upper limit of the second summation is the index of the first
summation, i.e:
sum_{j=0}^{x} sum_{i=0}^{j} choose(i+j, i)
where x variable or constant, doesn't matter.
The following code obviously doesn't work:
f=function(x) {j=0:x; i=0:j; sum( choose(i+j,i) ) }
Can you help?
Thanks
2007 Oct 17
2
Need help with function that includes 2 summation
I am relatively new to R, so this may be a much simpler question than it
seems to me. I am trying to create a function that includes two
summations, and can't figure out how. I am attaching the equation as a
pdf file. This function will then be optimized over a chosen range of
values, but right now I just need help with the function. Thank you.
Zack Darnell
Duke University
--
Zack
2006 Oct 03
1
Summation in R
Hello!
Maybe this is a trivial question as I'm still a new baby in R but I wish
that u will help me.
I want to calculate the following
U= sum (t_j*v_j)
where t_j is a vector
and v_j is the matrix
Thanks
Dina
2011 Jul 11
1
Summation resulting in a list?
Probability <- function(N, f, m, b, x, t) {
#N is the number of lymph nodes
#f is the fraction of Dendritic cells (in the correct node) that have the
antigen
#m is the number of time steps
#b is the starting position (somewhere in the node or somewhere in the gap
between nodes. It is a number between 1 and (x+t))
#x is the number of time steps it takes to traverse the gap
#t is the number
2016 Apr 08
1
write a function inside the summation in a more condensed form
Dear R Experts
that's my original equation
> x=c(2,4)
> Y1=sum(sapply(1:2,function(i){sum(sapply(1:i,function(j){(3^(x[i]+x[j]))}))}))
> y1
[1] 7371
I want to write the inside function (3^(x[i]+x[j])) in a more condensed form cause this will help me when the multiple summations are more than two
I've tried the following form
>
2012 Oct 26
3
summation sign
Hi all,
I have a very quick question on how to use the summation sign in R for the
function.
Here?s a basic example: the function is sum(i=1 to 5)log(1-xi^2)
Id be grateful if someone knows how to do this without writing it out 5
times - I am looking sth along the lines of the following:
computeR <- function(x)
{
return (-sum(log(1-x^2))
}^
thank you vm in advance!
--
View this
2004 Mar 16
3
multiple summation
Hello,
I have to compute a multiple summation (not an integration because the
independent variables a
are discrete) for all the values of a function of several variables f
(x_1,...,x_n), that is
sum ... sum f(x_1,...,x_n)
x_1 x_n
have you some suggestion? Is it possible?
I know that for multiple integration there is the function adapt, but it has at
most n=20. In my case n depends on the
2012 May 18
3
LM with summation function
Hi all,
I'm trying to model some data where the y is defined by
y = summation[1 to 50] B1 * x + B2 * x^2 + B3 * x^3
Hopefully that reads clearly for email.
Anyway, if it wasn't for the summation, I know I would do it like this
lm(y ~ x + x2 + x3)
Where x2 and x3 are x^2 and x^3.
However, since each value of x is related to the previous values of x, I
don't know how to do this.
2012 Oct 18
7
summation coding
I would like to code the following in R: a1(b1+b2+b3) + a2(b1+b3+b4) +
a3(b1+b2+b4) + a4(b1+b2+b3)
or in summation notation: sum_{i=1, j\neq i}^{4} a_i * b_i
I realise this is the same as: sum_{i=1, j=1}^{4} a_i * b_i - sum_{i=j} a_i
* b_i
would appreciate some help.
Thank you.
--
View this message in context: http://r.789695.n4.nabble.com/summation-coding-tp4646678.html
Sent from the R
2005 Jun 15
2
need help on computing double summation
Dear helpers in this forum,
This is a clarified version of my previous
questions in this forum. I really need your generous
help on this issue.
> Suppose I have the following data set:
>
> id x y
> 023 1 2
> 023 2 5
> 023 4 6
> 023 5 7
> 412 2 5
> 412 3 4
> 412 4 6
> 412 7 9
> 220 5 7
> 220 4 8
> 220 9 8
> ......
>
Now I want to compute the
2011 Jun 22
3
Help Needed on Merging Columns by Summation
Dear Sirs/Madam,
I am a beginner to R, and I am currently working on a data matrix which looks like this:
> head(oligo)
ko:K00001 ko:K00003 ko:K00005 ko:K00008 ko:K00009 ko:K00010 ko:K00012
AAA 370 631 365 67 164 455 491
KAA 603 1208 170 157 68
2006 Jan 21
1
A patch for do_sample: check replace arg
A colleague sent me the following:
If you specify probabilities in the 'sample' function and forget
to type 'prob=...', then you get nonsense. E.g.
sample(1:10,1,c(0,0,0,0,1,0,0,0,0,0))
does not filter '5', while
sample(1:10,1,prob=c(0,0,0,0,1,0,0,0,0,0))
does it correctly. I wish this would return an error because the
2010 Mar 20
2
summated scale
hello,
I am new to R (convert from Stata) and I am wondering if there is an R
command/function for generating a summated scale from, for example, four
separate variables in a data set. In other words, I want to transform the
variables x1, x2, x3, and x4 (which have high inter-item reliability) into
one new summated variable x'. Can't seem to find it in the psy or psych
package ...
2006 Nov 28
4
GAMS and Knots
Hi
I was wondering if anyone knew how to work out the number of knots that
should be applied to each variable when using gams in the mgcv library?
Any help or references would be much appreciated.
Thanks
Kathryn Baldwin
2013 Jan 17
2
create block diagonal with each rows
Dear R users,
I'd like to create a block diagonal matrix with each rows in a matrix.
Here is a simple example. (In fact, the matrix is big)
x <- matrix(1:20, 4,5)
> x
[,1] [,2] [,3] [,4] [,5]
[1,] 1 5 9 13 17
[2,] 2 6 10 14 18
[3,] 3 7 11 15 19
[4,] 4 8 12 16 20
With each rows in matrix x, I'd like to make the matrix below.
2004 Jul 30
3
getting values out of functions
Hi there,
Just wondering if there's a way to get a value you've
assigned within a function, out of the function?
For example,
function ()
{
testing <-read.table("...",header=TRUE)
}
I want to be able to use 'testing' outside of the function,
so be able to call ls() and testing be there...
Any ideas?
Thanks!
Kathryn
2013 Jan 16
3
matrix manipulation with its rows
Dear R users,
I have a question about matrix manipulation with its rows.
Plz see the simple example below
sample <- list(matrix(1:6, nr=2,nc=3), matrix(7:12, nr=2,nc=3),
matrix(13:18,nr=2,nc=3))
> sample
[[1]]
[,1] [,2] [,3]
[1,] 1 3 5
[2,] 2 4 6
[[2]]
[,1] [,2] [,3]
[1,] 7 9 11
[2,] 8 10 12
[[3]]
[,1] [,2] [,3]
[1,] 13 15 17
[2,]
2008 Oct 08
3
Re move repeated values
Dear R users,
I'd like to make this data
rem.y = c(-1,0,2,4,5)
from
y = c(-1,-1,0,2,2,2,2,4,4,5,5,5,5,5).
That is, I need to remove repeated values.
Here is my code, but I don't think it is efficient. How could I improve
this?
#------------------------------------------------------------------------
y = c(-1,-1,0,2,2,2,2,4,4,5,5,5,5,5)
n=length(y)
for (i in 1:n) #