Displaying 6 results from an estimated 6 matches for "janoska".
2011 Feb 25
5
Substituting inside expression
I am having following problem:
I?m constructing model for calculation of area of triangle.
I know sides a, b, and gamma angle.
I wish to calculate the area using heron?s formula:
S <- sqrt(s*(s-a)*(s-b)*(s-c))
where
s <- (a+b+c)/2
and c is calculated using law of cosines:
c <- sqrt(a^2 + b^2 -2*a*b*cos(gamma))
since i am calculating a regression model, i need derivation of this
2010 Sep 03
1
How to use lm() output for systemfit() 'Seemingly unrelated regression'
...e the problem is.
The problem remains even when I try:
> fo1 <- r98[,2] ~ f98[,1] + f98[,2] + ... + f98[,43]
> fo2 <- r98[,1] ~ f98[,1] + f98[,2] + ... + f98[,43]
instead of using lm()
Could someone give me a hand? I am quite new to R, so possibly the solutions
is simple:)
Thanks
Zbynek Janoska
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2010 Dec 16
2
How can I draw a line in empirical distribution function?
I've got the graphic with this:
a=c(120,40,75,85,55,75,55,90,90,55,155)
plot(ecdf(a))
How can I draw lines to show the lower quatile and upper quartil?
I only know there is the argument lines(),
but I don't know how to use it
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2011 Feb 28
3
Incorrectness of mean()
I have found following problem:
I have a vector:
> a <- c(1.04,1.04,1.05,1.04,1.04)
I want a mean of this vector:
> mean(a)
[1] 1.042
which is correct, but:
> mean(1.04,1.04,1.05,1.04,1.04)
[1] 1.04
gives an incorrect value.
how is this possible?
thanks,
zbynek
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2010 Dec 20
2
How to optimize function parameters?
Hi,
I have a dataset and I want to fit a function to it.
The function is variogram model (http://en.wikipedia.org/wiki/Variogram)
The variogram model is defined by three parameters and I want them to be
automatically optimized for real time data.
I tried to use gafit {gafit} for this, but there are some data
configuration, where optimal results given by gafit() are negative, which is
not correct
2011 Mar 25
0
applying random functions to multisets
Hi,
I am solving following problem:
Suppose I have some multiset:
> multiset <- c("a","a","c","d","d")
and rules, which operate with it (for simplicity not writen in R functions)
> rule1: "a" -> c("a","b")
> rule2: "a" -> c("a","c")
> rule3: "c" ->