I have an equation for a cylinder as $x^2+(y-b)^2=a^2$ for some $a$ and $b$.
so I just plugged in $b=2$ and $a=1$ and tried to plot it using wolfram alpha, and the 3D plot looked like half a cylinder, like this.
Why am I not getting a 3D plot for a cylinder instead?
Best Answer
The only way I've got for making WolframAlpha recognise this as a request for a 3D plot in which one variable happens to be absent, is:
This will not quite produce the right plot, but it's very close; I've had to add a term which is nearly zero, to make WA understand the $z$ term.
I have reported as a bug the fact that
ContourPlot3D[x^2+(y-2)^2==1, {x, -1, 1}, {y, 1, 3}, {z, -4, 4}]
is not recognised correctly.