I have a few equations that are rather long. They are 0 if the long part would become negative. Let's say they look something like $$ x =\begin{cases} a+b-cd &\quad \text{if}\ \ a+b-cd > 0\\0 &\quad \text{otherwise}.\end{cases} $$ Now I would prefer not to write the whole long part again. Is there a simple way of writing this? I was looking for something like $$ x =\begin{cases} a+b-cd &\quad \text{if}\ \ x>0\\0 &\quad \text{otherwise}.\end{cases}$$ In my case there is no way of simplifying the expression $a+b-cd$. Thanks for your help.
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$\begingroup$ This notation doesn't work because the value of $x$ is still undefined when you compare it to $0$. $\endgroup$– user65203Aug 13, 2018 at 9:11
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Superscript $\cdot^+$ is the way to go $$ x = (a + b - cd)^+ := \max(0, a + b - cd). $$
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$\begingroup$ that's exactly the definition of superscript +, as indicated in my answer. $\endgroup$– tortueAug 13, 2018 at 9:13