### I don't know shite about:

# There are some walls in my Math formula. |a|

## What's the meaning of variables surrounded by two vertical lines?

What does it mean if a variable in a Mathematics formula is surrounded by two vertical lines?

According to WolframAlpha *" |z| is the absolute value of z."*

I guess whether I take `|z|`

or `|a|`

doesn't really matter, so I'll continue with `|a|`

as it seems more common.

In laymen terms this the statement from WolframAlpha means we're taking the actual value from `a`

while disregarding the algebraic sign (`+`

or `-`

).

So if `a = -2.5`

then `|a|`

represents the value `2.5`

If `a = 3.14`

then `|a|`

equals the value `3.14`

You can see the two `|`

`|`

surrounding the variable name as some kind of programming function that returns the distance from `0`

to `a`

.
In-fact it exists in languages like `C#`

as the `{Math.Abs(value)}`

function.
But even if this function wouldn't exist in your programming language of choice you could implement it as `sqrt(a^2)`

(sqrt is the square-root).
Making `a`

squared gets rid of the algebraic sign (2*2 and -2*-2 are both 4). And the square root reverses the effect of the quadration without gaining back the algebraic sign.

In mathematical terms `|a|`

you may come across this notation described ast the `absolute value`

or `modulus`

of the real number `a`

.

In case you're looking for a more exhaustive definition, I can recommend this 3 part video by Eddie Woo.