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Version 1.3.1  (2001-08-31)

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> data(cars)
> library(nls)
> carfitnls <- nls(dist ~ a + speed^b, start=list(a=1,b=1), data=cars)
> summary(carfitnls)

Formula: dist ~ a + speed^b

Parameters:
  Estimate Std. Error t value Pr(>|t|)    
a -3.35701    4.44957  -0.754    0.454    
b  1.39114    0.02971  46.827   <2e-16 ***
---
Signif. codes:  0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1 

Residual standard error: 15.11 on 48 degrees of freedom

Correlation of Parameter Estimates:
        a
b -0.8771

>