[Rd] ugly in plotmath: frac(1, sqrt(...)) (PR#1101)

[ligges@statistik.uni-dortmund.de]

ligges@statistik.uni-dortmund.de wrote:
> 
> Sometimes (dependent on device and settings of 'cex' and 'lwd') the line
> of a square root symbol plottet in the denominator of a fraction appears
> to be in or above the line of the fraction.
> 
> Examples:
> 
> ### Choose one of these:
> # pdf("test.pdf", height=6, width=8)
> # bmp("test.bmp", width=1100, height=800, pointsize=12)
> # bitmap("test.tif", type="tiff24nc", width=12, height=9, res=300,
> pointsize=12)
> # png("test.png", width=1100, height=800, pointsize=12)
> # postscript("test.eps", height=6, width=8, horizontal=FALSE)
> 
>  par(cex=2, lwd=2)
>  plot(1:10)
>  text(2, 8, expression(frac(1, sigma[i]*sqrt(2*pi))))
> dev.off()

After some investigations:
In plotmath.c, line 2250 the "the gap between the nucleus and the
radical extension" is defined:
 #define RADICAL_GAP    0.4

It looks like this gap is not added to the hight (or included in the
calculations of the hight) of the denominator of a fraction. So the
whole denominator is located to close to the fraction bar, if a root is
drawn.
I don't see, how this can be fixed smartly ...

Uwe Ligges

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