# math notation for element-wise square root of vectors and matrices?

Discussion in 'Numerical Analysis' started by Felipe G. Nievinski, Mar 15, 2011.

1. ### Felipe G. NievinskiGuest

Please let me know if you are you aware of any established practice. I
don't want to end up having to type ".^(1/2)" in latex, even though
that's exactly what my matlab code looks like.
Thanks,
-F.

Felipe G. Nievinski, Mar 15, 2011

2. ### ImageAnalystGuest

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Is this a question about latex?

Well, anyway, your MATLAB code doesn't have to look like that. It can
look like this if you want:
sqrtOfMyMatrix = sqrt(myMatrix);

ImageAnalyst, Mar 15, 2011

3. ### Chip EasthamGuest

In a math write-up, you'll typically define a function,
say f:R^N_+ -> R^N_+ where (f(v))_i = sqrt(v_i).

That is, a function from the positive cone of R^N to
itself whose component-wise definition is taking the
square root.

Then you just refer in your write-up (formulas, etc.)
to f(v) for suitable vectors v as needed.

AFAIK this function isn't used frequently enough to
have a special name or notation, if that's what you're
asking. But that's very often the case when writing
math, even if the general topic is a well-known function
(but you are introducing a novel representation or an
analysis of an open problem).

regards, chip

Chip Eastham, Mar 15, 2011
4. ### Lee RudolphGuest

It's not a question about LaTeX, but it can be answered with
LaTeX.

aware of any established practice (and I doubt there is one,
at least for large values of "established"). Even if there
is (unless, when restricted to the editors, referees, and
likely readers of the paper being written, there *is* indeed
a very well established practice, which however has not made
itself known to me), the original poster ought seriously to
consider creating--and clearly describing in the text, before
its first use--an explicit nonce notation for the desired
concept: for instance, enclosing the (notation for) the
vector or matrix in large parentheses prefaced by the letters
"sqrt". That notation (and others achieving the same goal)
could easily be implemented in LaTeX without having to type
more than the definition of the appropriate macro, and one
instance of the macro per use of the notation.

Lee Rudolph

Lee Rudolph, Mar 15, 2011