graphing vertical line automatically

Thanks for trying, but first I don't use Prime (looks to me more like a preview version, lacking of symbolics, etc.).

I have played around with onerror, but it didn't worked out. Think, it is not intended to be used with symbolic expressions/evaluations. I can't catch an undefined function with it or an error in a function definition.

The main goal is that a linear equation is given in the Mathcad-usual form with the boolean equal sign. This equation could have the form y=a.x+b OR x=c and I want to graph it in both cases (and failed to graph it in the latter case). Any solutions are welcome.

On former occasions I often was searching for a possibility to manage part or all of an equation. E.g. extracting the lefthand or righthand side and assign it to a variable or applying an operation (e.g. adding the same term) on both sides of an equation. It would also have been helpful sometimes if I could transform an euqation or another mathematical term into a textstring, manipulate it there and transform it back. I guess, that these kinds of operations are not available in Mathcad because for MC an equation is a simple boolean expression which is subject to be evaluated, but not to be manipulated in the aforementioned ways. If that assumption is wrong and i simply missed the right way, please tell me.

Regards

WR

Thank you, Fred, think that was a helpful answer..

In your worksheet I don't see the vertical g(x) plotted, unless I change your 10^-15 up to 10^-5, which is still optically precise enough. Unfortunately in the original context there ist more than one equation which should be plotted and could be vertical and the equations are derived from a more complex situation. So it would be a lot more work to apply your approximation, but I think it could be done.

What I need/want are the exact(=symbolically) derived equations, but for graphing purpose an approximation like yours will suffice.

It would be helpful if there were a way to evaluate the boolean expression Eq and then decide, what to do, but it seems that this is not possible. I am thinking of something like "if LeftHandSideOf(Eq) is x then ..." or "if Eq is not solvable to y then ...". But it seems that this is beyond the possibilities of MC.

Thanks for your effort

WR