defining an expression in a point

[bdragon]

Hello, i'm sorry but i'm not english so i'll try to explain what i'm trying to do but bear with me if i'm not using the correct words.

I'm trying to find the symbol for defining an expression in a point. That is usually a scaled "rline" with the point of definition as a pedix (or apex + pedix in case it's "defined from point a to point b")

Right now it's not possible, i've tried using "right rline" and "left lline" and then using the "phantom" command to hide only the "left lline" but it does not work, it either hides everything or adds the question mark symbols, evidently i'm doing something wrong

I've also tried scaling the line with a " size +X "|" " but it comes up wrong (very thick) and then i can't add an unsized pedix, i've tried scaling the single character but it just does not work since if i de-scale the pedix then it attaches itself to the wrong position (that is: not at the bottom)

Right now i'm using stack{"|" # "|"_0} and similar, using the stacks to "scale" the vertical line to create some semblance of what i'm trying to obtain, but it's not right since there are one or more gaps between the lines of the stack

Is there a better option?

[Robert Tucker]

I'm afraid I don't really understand the maths you are trying to do; the only thing I can find on the net is:

http://www.latex-community.org/forum/viewtopic.php?f=19&t=2296

which seems to be a horizontal version of what you are trying to do vertically.

[bdragon]