# How to specify that if a denominator should not be 0

How can i specify in the otherwise condition of the following equation

\begin{cases}\ U & \text{if $A_{U_{Max}} = A_{U_{Min}} =$ Null},\\ \ \frac{A_{U_{Max}} - A_{U_{Min}}}{U\sqrt{2}} & \text{otherwise} \end{cases}

that if denominator is 0 then make it equal to 1 ?

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How about $U\sqrt{2}+\delta_{U\sqrt{2},0}$ (Kronecker's delta)? – Arturo Magidin Apr 17 '12 at 21:27
Or $U\sqrt2+[U\sqrt2=0]$, with an Iverson bracket. – Brian M. Scott Apr 17 '12 at 21:29

Replacing the denominator with $U\sqrt{2}+[U=0]$ (as suggested by Brian M. Scott) may be the shortest solution. However, keep in mind that the readers will have to mentally process the formula it by splitting into sub-cases anyway. So, consider refactoring the statement, e.g., Let $F=U$ if $A_{U_{Max}} = A_{U_{Min}} = 0$, and otherwise
$$F = \begin{cases} \frac{A_{U_{Max}} - A_{U_{Min}}}{U\sqrt{2}}, & \quad U\ne 0 \\ \ A_{U_{Max}} - A_{U_{Min}}, & \quad U = 0 \end{cases}$$