panel.qqmathline {lattice}  R Documentation 
Useful panel function with qqmath. Draws a line passing through the points (usually) determined by the .25 and .75 quantiles of the sample and the theoretical distribution.
panel.qqmathline(y, distribution, p = c(0.25, 0.75), ...)
y 
The original sample, possibly reduced to a fewer number of
quantiles, as determined by the f.value argument to
qqmath

distribution 
quantile function for reference theoretical distribution. 
p 
numeric vector of length two, representing probabilities. Corresponding quantile pairs define the line drawn. 
... 
other arguments. 
Deepayan Sarkar Deepayan.Sarkar@Rproject.org