Wikipedia:Reference desk/Archives/Mathematics/2010 July 3

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July 3

Notation for a non-derivative with prime (')

Let's say ${}_{\color {white}.}\varepsilon =X\cdot {Y}{\color {white}{\Big |}}\,\!$ and ${}_{\color {white}.}{\mbox{secondary }}\varepsilon =\varepsilon '={\frac {X}{Y^{2}}};{}_{\color {white}.}\,\!$.
What if, in certain cases, you want to identify $X\,\!$ and——therefore——${}_{\color {white}.}\varepsilon {\color {white}|}\,\!$, with respect to $\lambda \,\!$?: ${\color {white}{\Big |}}\varepsilon (\lambda )=X\cdot {Y}(\lambda )\,\!$. But what about ${}_{\color {white}.}\varepsilon '\,\!$? Is there a standard/established modification for the non-derivative $\varepsilon '\,\!$, maybe $\varepsilon (\lambda )'\,\!$ or $\varepsilon '|(\lambda ){}_{\color {white}.}\,\!$? $(\varepsilon ')(\lambda ){}_{\color {white}.}\,\!$ seems awkward. P=|  ~Kaimbridge~ (talk) 18:06, 3 July 2010 (UTC)

It would just be $\varepsilon '(\lambda )$. You just have to tell that it isn't a derivative from context. If the context isn't clear enough, then don't use primes to distinguish between functions. Use ${\tilde {\varepsilon }}$ or something. --Tango (talk) 18:22, 3 July 2010 (UTC)