mjhjmtu

I have been looking at other posts and have modified my code accordingly, but I still can't get it to work. I think there is an issue that has not been addressed in any of the posts that I have found. However, I don't know what the issue is, so I can't make a specific inquiry.

 begintikzpicture
 beginaxis[xmax = 4,ymax = 3,samples = 50]
 draw[black, smooth, variable=x] plot (x,sqrt(1 - 4(x - frac12)^2);
 endaxis
 endtikzpicture

OK, this is too long for a comment. There are several issues:

• You say variable=x but one x does not have a backslash.


• You need to add multiplication signs.


• You cannot use frac in an expression that is going to be parsed. frac is used to typeset fractions.

Altogether, the expression should be (I guess) sqrt(1 - 4*(x - 1/2)^2. However, as you are using an axis environment, I think you are loading pgfplots, so I'd suggest

documentclass[tikz,border=3.14mm]standalone
usepackagepgfplots
pgfplotssetcompat=1.16
begindocument
begintikzpicture
beginaxis[xmax = 4,ymax = 3,samples = 50]
 addplot[black, smooth,domain=0:1] sqrt(1 - 4*(x - 1/2)^2;
endaxis
endtikzpicture
enddocument

documentclassstandalone
usepackagepgfplots
begindocument
begintikzpicture
beginaxis[xmax=10,ymax=10, samples=1000]
 addplot+[mark=none,samples=200,unbounded coords=jump] sqrt(x);
endaxis
endtikzpicture
enddocument

I would suggest to do something like this