[R] Very inaccurate circles

[Juan Alonso]

Hello,

Please take a look at the attached plot and let me know if this is
normal. The circle has radio  I am using R 2.9.2 inside OS X Leopard.

The plot was generated with:

png('bizarre_circle.png')
plot(c(-5,0,0,5), c(0,5,-5,0))
symbols(0,0, circles=c(sqrt(25)), inches=FALSE, add=TRUE)
dev.off()

If I resize the x11's plot window I can manage to make the circle pass
through all the points but it's the first time I have to do this. I
understand this may be happening because of the method to draw
circles. I googled and found this other methods:

http://tolstoy.newcastle.edu.au/R/help/03a/3364.html

But method 2 and method 3 seem to use different units than my points
and working with them is not so straightforward.

1. Is there a way to draw circles in the same unit system than plot
already uses?

2. Is there a way of making method 3 (which uses mm) work with the
same unit system as the plot?

Thank you,

-- 
slnc
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