Hi,
Im trying to perform a time series analysis on financial data. Im going on the
assumption that it follows the random walk, and therefore am fitting an ARIMA
process via the following code fit<-arima(exchange,order=c(0,1,0)), and then
analysing the tsdiag.
Is there a more efficient way of
Hi Guys,
Im trying to find the exponential of a matrix.
Can someone please help me do this?
Thanks a lot
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Hey guys,
im sort of a beginner with R, but here's what i need to do.
i need to perform a time series analysis on a set of financial data that i've
been given. im trying to look at the ACF and PACF and fit it to a particular
model (i think its the ARIMA model because i've read that financi
Hey guys,
im sort of a beginner with R, but here's what i need to do.
i need to perform a time series analysis on a set of financial data that i've
been given. im trying to look at the ACF and PACF and fit it to a particular
model (i think its the ARIMA model because i've read that financial d
Hi Guys,
i think this is a relatively simple question.
I have coded the following polynomial function
y= function(x) x^3-2*x^2+1
I need to find the inverse of this, but the code i am using now isnt returning
what i want it to.
What is the general code for finding an inverse function?
Thanks
Hey guys, sorry im drawing a mental blank.
i have coded the function:
y <- function(x) 6*x^4-(1*x^2)^3
How do i evaluate this function for a given x?
i know this is a ridiculous question, but thanks anyway
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[[elided
Hey Guys,
i have the sample variances for 1000 samples, and i want to fit it to a
chi-squared distribution.
after making a loop for the simulation initially, i have the following code to
compute the variances
samples = replicate(n, rnorm(m, 0, 1), simplify=FALSE)
variances = sapply(samples, va
Hi,
> g=list()
> for(i in 1:1000){z[[i]]=rnorm(15,0,1)}
I've attempted a similar problem based on the above method. Now, if i want to
find the sample variance, do i go about it like this?
> for (i in 1:1000)vars[[i]] = sum(z[[i]])
> vars[[i]]
the overall sigma squared will just be 1, because
Hi peter,
Quite an insight you have there hehe. i am continuing on from the orignal
problem of creating a simulation.
Im now trying to find (nâ1)S2/Ï2, and fit it to a chi squared dist with 5
degrees of freedom.
im having trouble with the coding for this. i think for the second part of th
rick (form a matrix and use apply()) can also be used to get
> multi-parameter stats, 'cos apply will return a matrix or list if the
> function returns a vector or list.
>
> The only snag is the memory usage; for large simulations that can be a
> problem. If it is, resorting to loopi
Hey Guys,
i need 1000 samples of size 15, for distributions of Exp(1) and Norm(0,1). here
is what i have done so far.For the exponential
z<-list()
for(i in 1:1000){z[[i]]=rexp(15,1)}
For the Normal
y<-list()
for(i in 1:1000){y[[i]]=rnorm(15,0,1)}
Is this correct?
after this i need to compu
Hey guys, i have a relatively simple problem.
I need to use netwon's method to find the root of a polynomial, lets say
x^3-2x-1
i start off with
p <- function(x) x^3-2*x-1
My method, which im sure is very amateur, is to type another function, which is
the derivative of p, and after picking a
Hi Guy,
I am having trouble graphing the following function
â2Î(n/2)/[ân â 1Î((n â 1)/2 for the values of n between 2 and 50.
i know that Î(n) = (n-1)!, which in R is factorial(n-1)
When i type that into R, using y <- function(n).
and then plot(y,2,50), it doesnt give me anythin
Hey,
I am having trouble graphing the following function
â2Î(n/2)/[ân â 1Î((n â 1)/2 for the values of n between 2 and 50.
i know that Î(n) = (n-1)!, which in R is factorial(n-1)
When i type that into R, using y <- function(n).
and
then plot(y,2,50), it doesnt give me anything m
hey guys, i've been following this discussion about the simulation, and being a
beginner myself, im really unsure of the best method.
I hve the same problem as the initial one, except i need 1000 samples of size
15, and my distribution is Exp(1). I've adjusted some of the loop formulas for
hey guys, i've been following this discussion about the simulation, and being a
beginner myself, im really unsure of the best method.
I hve the same problem as the initial one, except i need 1000 samples of size
15, and my distribution is Exp(1). I've adjusted some of the loop formulas for
Hi,
Does anyone know how to code newton's method for finding the roots of
polynomial functions? im not sure whether i need to do this manually, or just
code something with a loop to stop when it gets to the desired result
thanks guys!
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ns
method of finding a root for this.
Please help.
Regards,
Kon Knafelman
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