# Proper representation for a conditional function

I have a function shown in below image. But the 2nd line (the parenthesis) has something that I don't know how to formulate properly.

The equation (I was not allowed to post images directly)

1- Does this count as a piecewise function?

Thanks.

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What if two of the $R$s are zero? –  user7530 Jan 22 '13 at 8:14
Write the equation down please... –  draks ... Jan 22 '13 at 8:25
@user7530: only one of them can be 0. It has a physical concept that I omitted to avoid making things more complex. –  wmac Jan 22 '13 at 9:00
@darks: it is a model I have created. host111.com/files/equation1.jpg –  wmac Jan 22 '13 at 9:01
I wouldn't try to write a one-line definition of $M_i$. That's bound to end up confusing.
Instead I might first define $d(R)$ to be the least index $i$ for which $R_i=0$, or $0$ if none of the $R_i$ are zero. Then I would write, e.g.,
$$M_i(R) = \begin{cases}F(R_i) & d(R) = 0\\1 &d(R) = i\\0 & \textrm{otherwise.}\end{cases}$$