EVOLUTION-MANAGER
Edit File: SSgompertz.html
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><title>R: Self-Starting Nls Gompertz Growth Model</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="R.css" /> </head><body> <table width="100%" summary="page for SSgompertz {stats}"><tr><td>SSgompertz {stats}</td><td style="text-align: right;">R Documentation</td></tr></table> <h2>Self-Starting Nls Gompertz Growth Model</h2> <h3>Description</h3> <p>This <code>selfStart</code> model evaluates the Gompertz growth model and its gradient. It has an <code>initial</code> attribute that creates initial estimates of the parameters <code>Asym</code>, <code>b2</code>, and <code>b3</code>. </p> <h3>Usage</h3> <pre> SSgompertz(x, Asym, b2, b3) </pre> <h3>Arguments</h3> <table summary="R argblock"> <tr valign="top"><td><code>x</code></td> <td> <p>a numeric vector of values at which to evaluate the model.</p> </td></tr> <tr valign="top"><td><code>Asym</code></td> <td> <p>a numeric parameter representing the asymptote.</p> </td></tr> <tr valign="top"><td><code>b2</code></td> <td> <p>a numeric parameter related to the value of the function at <code>x = 0</code></p> </td></tr> <tr valign="top"><td><code>b3</code></td> <td> <p>a numeric parameter related to the scale the <code>x</code> axis.</p> </td></tr> </table> <h3>Value</h3> <p>a numeric vector of the same length as <code>input</code>. It is the value of the expression <code>Asym*exp(-b2*b3^x)</code>. If all of the arguments <code>Asym</code>, <code>b2</code>, and <code>b3</code> are names of objects the gradient matrix with respect to these names is attached as an attribute named <code>gradient</code>. </p> <h3>Author(s)</h3> <p>Douglas Bates</p> <h3>See Also</h3> <p><code><a href="nls.html">nls</a></code>, <code><a href="selfStart.html">selfStart</a></code> </p> <h3>Examples</h3> <pre> DNase.1 <- subset(DNase, Run == 1) SSgompertz(log(DNase.1$conc), 4.5, 2.3, 0.7) # response only local({ Asym <- 4.5; b2 <- 2.3; b3 <- 0.7 SSgompertz(log(DNase.1$conc), Asym, b2, b3) # response _and_ gradient }) print(getInitial(density ~ SSgompertz(log(conc), Asym, b2, b3), data = DNase.1), digits = 5) ## Initial values are in fact the converged values fm1 <- nls(density ~ SSgompertz(log(conc), Asym, b2, b3), data = DNase.1) summary(fm1) plot(density ~ log(conc), DNase.1, # xlim = c(0, 21), main = "SSgompertz() fit to DNase.1") ux <- par("usr")[1:2]; x <- seq(ux[1], ux[2], length.out=250) lines(x, do.call(SSgompertz, c(list(x=x), coef(fm1))), col = "red", lwd=2) As <- coef(fm1)[["Asym"]]; abline(v = 0, h = 0, lty = 3) axis(2, at= exp(-coef(fm1)[["b2"]]), quote(e^{-b[2]}), las=1, pos=0) </pre> <hr /><div style="text-align: center;">[Package <em>stats</em> version 3.6.0 <a href="00Index.html">Index</a>]</div> </body></html>