Displaying 4 results from an estimated 4 matches for "calculationg".
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calculations
2003 Feb 26
1
calculationg condition numbers
am I right in the assumption, that for calculation of the condition
numbers I have to use the correlation matrix of X, and not t(x) %*% x?
> e <- eigen(t(x) %*% x)
better (x must not have a first column of ones):
> e <- eigen(cor(x))
> e$val
[1] 6.6653e+07 2.0907e+05 1.0536e+05 1.8040e+04 2.4557e+01 2.0151e+00
> sqrt(e$val[1]/e$val)
[1] 1.000 17.855 25.153 60.785 1647.478
2010 Jun 14
2
recursive function
Dear list,
I have the following problem, what i'm trying to do is to built a function which does the following calculationg in a recursive way:
I have a data frame more or less like this:
variable year DELTA
EC01 2006 /
EC01 2007 10
EC01 2008 5
EC01 2009 9
And then I have at time 2009 a variable called R_EC01...
2004 Jan 29
2
Calculating/understanding variance-covariance matrix of logistic regression (lrm $var)
...sult: 0
# looking at the problem:
cov
-----------------
Result:
Intercept V
Intercept 0.7759040 -0.12038969
V -0.1203897 0.02274177
(***)
fit$var is the estimated variance-covariance matrix.
How is it calculated? (Meaning of intercept and x?)
Does anybody know how calculationg this "by hand" or
can give me a reference (preferable in the internet)?
Thanks!
Karl.
2006 Aug 09
2
Speeding indexing and sub-sectioning of 3d array
Hi,
I am having a problem with a very slow indexing and sub-sectioning of a 3d
array:
> dim(arr)
[1] 245 175 150
For each point in the array, I am trying to calculate the mean of the values
in its surrounding:
mean( arr[ (i - radius):(i + radius),
(j - radius):(j + radius),
(k - radius):(k + radius)] )
Putting that code in 3