# tilde symbol under a variable

• September 8th 2011, 06:23 PM
wik_chick88
tilde symbol under a variable
how do i "underline" x with a tilde (the ~ symbol)?
• September 8th 2011, 06:34 PM
Plato
Re: tilde symbol under a variable
Quote:

Originally Posted by wik_chick88
how do i "underline" x with a tilde (the ~ symbol)?

Don't know what you want, but:
[TEX]\underline{~x}[/TEX] or [TEX]\underline{\~x}[/TEX] or [TEX]\underline{\sim x}[/TEX] gives
$\underline{~x}$ or $\underline{\~x}$ or $\underline{\sim x}$
• September 8th 2011, 06:40 PM
wik_chick88
Re: tilde symbol under a variable
sorry, i realise how i worded it wrong. i want to put the ~ symbol underneath the x rather than on top of it
• September 8th 2011, 06:43 PM
alexmahone
Re: tilde symbol under a variable
Quote:

Originally Posted by wik_chick88
sorry, i realise how i worded it wrong. i want to put the ~ symbol underneath the x rather than on top of it

The tilde is placed on top of a symbol to indicate some special property. Why would you want to place it below a symbol?
• September 8th 2011, 06:44 PM
wik_chick88
Re: tilde symbol under a variable
well i want to specify that x is a vector. sometimes in my notes it has the ~ symbol underneath it, sometimes it is in bold (which i don't know how to do either)
• September 8th 2011, 06:45 PM
alexmahone
Re: tilde symbol under a variable
Quote:

Originally Posted by wik_chick88
well i want to specify that x is a vector. sometimes in my notes it has the ~ symbol underneath it, sometimes it is in bold (which i don't know how to do either)

The usual way to denote a vector v is \vec v, which yields $\vec{v}$.
• September 8th 2011, 06:47 PM
Plato
Re: tilde symbol under a variable
Quote:

Originally Posted by wik_chick88
sorry, i realise how i worded it wrong. i want to put the ~ symbol underneath the x rather than on top of it

[TEX]\mathop x\limits_ \sim [/TEX] gives $\mathop x\limits_ \sim$
• September 9th 2011, 01:21 AM
Opalg
Re: tilde symbol under a variable
Quote:

Originally Posted by wik_chick88
how do i "underline" x with a tilde (the ~ symbol)?

This is not easy in TeX. Part of the problem is that the tilde is a reserved character in TeX, which means that it is very hard to display it (except through the \tilde command, which produces an accent above a letter). The only way I can get it to appear underneath a character is to use Plato's idea in the previous comment, which produces something similar to a tilde by using the \sim symbol. The difficulty then is to get it to appear under an x, without raising the x, and without looking too big or too far underneath the x. The best I can manage is

[TEX]a \underset{^\sim}x b[/TEX]

which produces

$a \underset{^\sim}x b$.

Even then, the tilde is a long way below the x. I think you would probably do better to use an alternative notation.
• September 9th 2011, 06:54 AM
CaptainBlack
Re: tilde symbol under a variable
Quote:

Originally Posted by wik_chick88
well i want to specify that x is a vector. sometimes in my notes it has the ~ symbol underneath it, sometimes it is in bold (which i don't know how to do either)

Such notations are to denote a bold character in hand written material, more usual is an underscore. If you are setting stuff in LaTeX just make it bold.

CB
• September 9th 2011, 07:09 PM
Ackbeet
Re: tilde symbol under a variable
Quote:

Originally Posted by CaptainBlack
Such notations are to denote a bold character in hand written material, more usual is an underscore. If you are setting stuff in LaTeX just make it bold.

CB

Which you can do on this forum by doing

[TEX]\mathbf{x}[/TEX], which renders

$\mathbf{x}$.