search for: hyperbola

...in.com/Xhg0RaUp There is some jitter in the data, but mostly it looks like a hockey puck curve. It does not get converted into a straight line when I tried log conversions, so it does not seem to be a power series relationship. My expectation is that the data will fit a curve that is a hyperbola, but I don't know how to formulate that regression. How does one fit data to a general function AX^2 + Bxy + Cy^2 +D = 0 I have tried polynomial functions and inverse functions lm2 = lm(Time ~ Requests + I(Requests^2) + I(Requests^3)) but that does not appear to be close....

...llo. I am working on an analysis involving the nonlinear mixed model function (nlme) in R. The data consist of measures of carbon fixation by leaves as a function of light intensity and the parametric function (standard in this area because it has a biological interpretation) is a non-rectangular hyperbola. I cannot get the nonlinear mixed model (nlme) function to converge cleanly. I am hoping that others have found strategies for getting starting values that might solve this problem. I have a request (below), some details of the problem, and then a question (at the end of this posting). Reques...

...g the syntax of nls() when the nonlinear function within the call is specified outside of nls(). Sundar showed me how to do this. Now I have a slightly more complex problem that is analogous to a broken-stick regression but in a non-linear context. I want my data to be fit to a non-rectangular hyperbola if the value of the independent variable (I) is less than some value (“Icut”, to be estimated) and to be fit to a constant value (to be estimated) if the value of the independent variable is greater than or equal to “Icut”. That is, if the value of the independent variable is less than Icut, then f...

Does anyone know how to graph a line according to a specified equation? I'd like to plot the following hyperbola: Y=139.35/(1+(0.174*X)) I know there's a way to do this, but I'm having a ridiculous time trying to remember how. Thanks! Kyle H. Ambert Department of Behavioral Neuroscience Oregon Health & Science University [[alternative HTML version deleted]]

I have got a data set that is Gross Primary Productivity ~ Total Suspended Solids it is a hyperbola just like: plot(1/c(1:1000)) how do I model this relationship so that I can get all of the neat things that lm gives residuals etc. etc. so that I can see if my eyeball model stands up. Thanks for any help, pointers, or good things to read. -- Stephen Sefick Research Scientist Southeastern Natu...

Hello. I am trying to fit a non-rectangular hyperbola function to data of photosynthetic rate vs. light intensity. There are 4 parameters that have to be estimated. I find the nls function very difficult to use because it often fails to converge and then gives out cryptic error messages. I have tried playing with the control parameters but this doe...

Hello. Following pages 342-347 of Pinheiro & Bates, I am trying to write a self-starting nonlinear function (a non-rectagular hyperbola) to be used in nonlinear least squares regression (and eventually for a mixed model). When I use the getInitial function for my self-starting function I get the following error message: > getInitial(photo~NRhyperbola(Irr,theta,Am,alpha,Rd),dat) Error in tapply(y, x, mean, na.rm = TRUE) :...

Hello. I am having a problem setting up a self-starting function for use in nonlinear regression (and eventually in the mixed model version). The function is a non-rectangular hyperbola - called "NRhyperbola" - which is used for fitting leaf photosynthetic rate to light intensity. It has one independent variable (Irr) and four parameters (theta, Am, alpha and Rd). I have created this to act as a self-starting function. The self-starting function seems to work (i.e. when...

Dear R People: Could someone recommend a small example for spline regression, please? I would like to show this to my students, step by step. Thanks in advance, Erin -- Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown mailto: erinm.hodgess at gmail.com

...pages 342-347) describe how to construct a self-starting function for use in nls, nlsList and nlme. A self-starting function provides, not only the function to be evaluated, but also estimates of initial values of the parameters that are to be estimated. I have written a self-starting function (NRhyperbola) for a non-rectangular hyperbola with 4 parameters (theta, Am, alpha, Rd). The function works: > getInitial(Photosynthese~NRhyperbola(Irr,theta,Am,alpha,Rd),data=lit.dat a2,na.action=na.omit) theta Am alpha Rd 0.69495045 35.32201003 0.03156335 1.26873011...

Dear R Community, I am plotting this simple x-y plot (raw data & plot attached). I cant fit a linear regression line to it. I have to figure out what is the best fit for this graph. Is there a way to tell which regression to use for this kind of data? Also, after selecting the best fit model, I need to extrapolate what could be the other possible data points. I am new to R. Could anyone

...Frechet Distribution Family Function freund61 Freund's (1961) Bivariate Extension of the Exponential Distribution gamma1 1-parameter Gamma Distribution gamma2 2-parameter Gamma Distribution gammahyp Gamma Hyperbola Bivariate Distribution gaussianff Gaussian (normal) Family Function genbetaII Generalized Beta Distribution of the Second Kind genpoisson Generalized Poisson distribution geometric Geometric Distribution gev Generalized Extre...

...oject.org> Message-ID: <DAE7D8B9-0991-4DF7-8336-F22CA23E1254@auckland.ac.nz> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed On 21/09/2008, at 10:38 AM, Peter Dalgaard wrote: > stephen sefick wrote: >> I am not sure if I am exaggerating or not read title as hyperbola >> >> On Sat, Sep 20, 2008 at 2:20 PM, stephen sefick >> <ssefick@gmail.com> wrote: >> >>> I have got a data set that is Gross Primary Productivity ~ Total >>> Suspended Solids it is a hyperbola just like: >>> plot(1/c(1:1000)) >>>...