Displaying 20 results from an estimated 10000 matches similar to: "How code for an exponential function"
2017 Aug 16
1
Bias-corrected percentile confidence intervals
Hi folks,
I'm trying to estimate bias-corrected percentile (BCP) confidence
intervals on a vector from a simple for loop used for resampling. I am
attempting to follow steps in Manly, B. 1998. Randomization, bootstrap
and monte carlo methods in biology. 2nd edition., p. 48. PDF of the
approach/steps should be available here:
https://wyocoopunit.box.com/s/9vm4vgmbx5h7um809bvg6u7wr392v6i9
If
2012 Jun 04
2
Non-linear curve fitting (nls): starting point and quality of fit
Hi all,
Like a lot of people I noticed that I get different results when I use nls
in R compared to the exponential fit in excel. A bit annoying because often
the R^2 is higher in excel but when I'm reading the different topics on this
forum I kind of understand that using R is better than excel?
(I don't really understand how the difference occurs, but I understand that
there is a
2010 Jun 28
1
Exponential Smoothing: Forecast package
Hey,
I am using the ets() function in the forecast package to find out the best
fit parameters for my time-series. I have about 50 sets of time series data.
I'm currently using the function as follows:
ets(x,model="AZZ",opt.crit="mse")
As to my observation about 5-10 of them have been identified by ets to have
a trend and an alpha, beta values have been thrown up -
2008 Aug 29
1
nls() fails on a simple exponential fit, when lm() gets it right?
Dear R-help,
Here's a simple example of nonlinear curve fitting where nls seems to get
the answer wrong on a very simple exponential fit (my R version 2.7.2).
Look at this code below for a very basic curve fit using nls to fit to (a)
a logarithmic and (b) an exponential curve. I did the fits using
self-start functions and I compared the results with a more simple fit
using a straight lm()
2011 Jun 14
2
How to generate bivariate exponential distribution?
Any one know is there any package or function to generate bivariate
exponential distribution? I gusee there should be three parameters, two rate
parameters and one correlation parameter. I just did not find any function
available on R. Any suggestion is appreciated.
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2008 Nov 11
3
exponential of a matrix
Is the matrix exponential available in some package?
The cannonical reference is "Nineteen dubious ways to take the exponential of a matrix". (Love that title)
Terry T.
2006 Sep 12
4
variables in object names
Is there any way to put an argument into an object name. For example,
say I have 5 objects, model1, model2, model3, model4 and model5.
I would like to make a vector of the r.squares from each model by code
such as this:
rsq <- summary(model1)$r.squared
for(i in 2:5){
rsq <- c(rsq, summary(model%i%)$r.squared)
}
So I assign the first value to rsq then cycle through models 2 through
2005 Aug 10
2
Exponential, Weibull and log-logistic distributions in glm()
Dear R-users!
I would like to fit exponential, Weibull and log-logistic via glm() like
functions. Does anyone know a way to do this? Bellow is a bit longer
description of my problem.
Hm, could family() be adjusted/improved/added to allow for these distributions?
SAS procedure GENMOD alows to specify deviance and variance functions to
help in such cases. I have not tried that option and I do not
2010 Jun 29
1
Model validation and penalization with rms package
I?ve been using Frank Harrell?s rms package to do bootstrap model
validation. Is it the case that the optimum penalization may still
give a model which is substantially overfitted?
I calculated corrected R^2, optimism in R^2, and corrected slope for
various penalties for a simple example:
x1 <- rnorm(45)
x2 <- rnorm(45)
x3 <- rnorm(45)
y <- x1 + 2*x2 + rnorm(45,0,3)
ols0 <- ols(y
2010 Jan 08
2
R exponential regression
Hi all,
I have a dataset which consists of 2 columns. I'd like to plot them on a x-y
scatter plot and fit an exponential trendline. I'd like R to determine the
equation for the trendline and display it on the graph.
Since I am new to R (and statistics), any advice on how to achieve this will
be greatly appreciated.
Many thanks,
Chris
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2004 Feb 03
1
Error in f(x, ...) : subscript out of bounds
R-Listers:
I am doing a quasi-maximum likelihood estimation and I get a "subscript
out of bound" error message, Typically I would think this means that a
subscript used in the function is literally out of bounds however I don't
think this is the case. All I change in the code is a constant, that is
hard-wired in (not data dependent and not parameter dependent),
furthermore,
2008 Dec 01
1
Parameters of exponential power density
Hello!
I must estimate the parameters of a exponential power density. There is the
normalp package, but this works only for a shape parameter bigger than 1.
But what should i do if the shape parameter is less than 1? (Sorry for my
english)
Thank you very much for help!
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2011 Nov 29
3
Negative exponential fit
We need help....
We are doing a project for a statistical class in and we are looking at
world record times in different running events over time. We are trying to
fit the data with a negative exponential but we just cant seem to get a
function that works properly.
we have on our x-axis the date and on the y-axis the time(in seconds). So as
you can imagine, the times have decreased and appear to
2010 May 09
3
Plotting log-axis with the exponential base to a plot with the default logarithm base 10
Hello!
I have a problem which I have tried to solve for several days now..
I have plottet a lineplot.CI in the library "sciplot", and I am trying to
plot it with a logaritmic y-axis (with exponential base).
The problem is that; when I type "log "y"", the axis transforms into the
logaritmic of base 10.
I wonder if someeone could tell me how to specify that I would
2007 Mar 11
1
fitting a mixed exponential distribution
Hi all,
I am attempting to fit, and test the goodness of fit of, a mixed
exponential distribution to my dataset which consists of 15minute
rainfall intensity data. FYI, the dataset spanning approx.2 years and
7 rainfall stations consists of some three hundred thousand 15min data
records, of which some 30 thousand are non-zero rainfall amounts.
Could anyone please tell me how i could do
2006 Apr 18
1
Compare two Power law or Exponential distributions
Dear All,
I'd like to compare exponential or power-law distributions.
To do so, people are often referred to the ks.test. However,
I imagine ks.test wouldn't be as powerful as a test specifically
designed for a distribution type.
So my question is, is there a more specific test for each of
these distribution? (exponential or power-law)
Thanks for your hints!
E
2006 Sep 27
1
exponential fitting
Hi,
I would like to fit some experimental points by a exponential function.
I ignore the parameters of this exponential and what I would like is to
ask R to calculate the best fitting curve an the associated parameters (as
the linear model function (lm) does for linear models).
Is it possible ?
Do anyone have an idea about how to do that ?
Thanks by advance
Jessica Gervais
[[alternative
2008 Dec 10
1
mixed exponential distribution
Good morning,
Is there anyway to do Mixed Exponential Distribution in R? I am trying
to load some lag-weighted empirical survival distribution into R and run
a mixed exponential on that data.
Thanks,
Jacob Fazekas
Jacob Fazekas
Assistant Actuary
Auto-Owners Insurance Company
517-703-2543
fazekas.jacob@aoins.com
[[alternative HTML version deleted]]
2011 Mar 21
2
Exponential distribution
Dear R-users,
I have to plot a exponential distribution like the plot in the pdf
attached. I've write this code but I don't know how to draw the two lines..
Can anyone help me please?
Thank you very much
Pippo http://r.789695.n4.nabble.com/file/n3394476/exponential_smoothing.pdf
exponential_smoothing.pdf
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2003 Jun 10
2
fitting data to exponential distribution with glm
I am learning glm function, but how do you fit data using exponential
distribution with glm?
In the help file, under "Family Objects for Models", no ready made option
seems available for the distribution as well as for other distributions
satisfying GLM requirements not listed there.