Ask Whether The Plot Step function variation $x + \lfloor x \rfloor$ is Correct

General Usage
1

Hi all I try to plot this function: x + \lfloor x \rfloor

I have this code:

using Plots,LaTeXStrings,Colors
gr()

f(x) = x + floor(x)
x = -2:1:4
y = f.(x)
plot(x[1:2], [y[1], y[1]], label=L"f(x) = x + \lfloor x \rfloor", legend=:topleft,legend_foreground_color=:white, legend_font_color=:blue3, color=:blue3, showaxis=false, tickfontcolor=:white)
# axis and 
hline!((0,0), color=:black, label="")
vline!((0,0), color=:black, label="")
for i in x
	if i!= 0
		annotate!(i,-0.2, (i, 7))
	end
end
for i in y
	if i != 0
		annotate!(-.2, i, (i, 7))
	end
end
annotate!(-.2, -.2, ("0", 7))
for i in 2:length(x)-1
	plot!(x[i:i+1], [y[i], y[i]], label="", color=:blue3, lw=2)
	scatter!(x[i], y[i], marker=:circle, markersize=8, label="")
end
scatter!(x[1:end-1], y[1:end-1], markersize=3, markercolor=:blue4, label="")
scatter!(x[2:end], y[1:end-1], markersize=3, markercolor=:white, label="")

resulting in this:
Capture d’écran_2022-11-20_14-47-15

I doubt the plot I made since the book shows the plot of so called function to be like this:
Capture d’écran_2022-11-20_14-50-58

Which one is correct ? If the latter, please tell me how to achieve that plot. Thanks a lot!

2

Seems like there is a wrong index, it should be

	plot!(x[i:i+1], [y[i], y[i+1]], label="", color=:blue3, lw=2)
1 Like
3

No the index is right, because it will make the step function that way.

Anyway the fault is on me. The function is actually x + |x|.

I already find the solution thanks!