Shading the solution of quadratic inequality
I'm not sure exactly what sort of plot was desired, but I'll offer 1.5 possibilities. Currently you can do something like this: require(mosaic) plotFun( x^2 - 4 ~ x , xlim=c(-6,6), col='blue' ) plotFun( (x^2 - 4)/as.numeric(x^2 -4 > 0) ~ x , xlim=c(-6,-2), add=TRUE, col='blue', lwd=4 ) It is a bit of kludge since I'm using division by 0 to hide part of the function. You can adjust colors, line thickness, and alpha to your particular sensitivities. And you can use type='h' if you want a "filled in version". Soon, you should be able to do plofFun( x^2 - 4 ~ x, groups=(x^2-4>0) ) If you find yourself wanting to plot "mathematical" functions like this, I encourage you to give plotFun() a try and let us know how you like it. ---rjp
On Feb 16, 2012, at 9:42 AM, R. Michael Weylandt wrote:
You should probably say more about which graphics engine you are using, but here's a start: curve(x^2-4, from = -3, to = 3) x <- seq(-3, 3, length.out = 200) polygon(c(x, rev(x)), c(x^2-4, rep(Inf, length(x))), col = 2) The red is a little "oppressive" so I'd try to add transparency if your device supports it. Adding a shade above/below argument to curve based on the same principles might be a fun exercise too... Michael On Thu, Feb 16, 2012 at 9:13 AM, AbouEl-Makarim Aboueissa <aaboueissa at usm.maine.edu> wrote:
Dear all R Users:
How can I shade the solution (-Inf,-2) or (2,Inf) of the inequality
-x^2+4<0 within the curve of f(x)=-x^2+4.
and
the solution (-Inf,-2)or(2,Inf) of the inequality x^2-4>0 within
the curve of
f(x)=x^2-4.
with many thanks
abou
==========================
AbouEl-Makarim Aboueissa, Ph.D.
Associate Professor of Statistics
Graduate Program Coordinator
Department of Mathematics & Statistics
University of Southern Maine
96 Falmouth Street
P.O. Box 9300
Portland, ME 04104-9300
USA
Tel: (207) 228-8389
Fax: (207) 780-5607
Email: aaboueissa at usm.maine.edu
aboueiss at yahoo.com
Office: 301C Payson Smith
[[alternative HTML version deleted]]
_______________________________________________ R-sig-teaching at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-sig-teaching
_______________________________________________ R-sig-teaching at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-sig-teaching