# Custom display for constructed functions

In a similar vein to my previous question, is it possible to define a function that displays differently to its default? eg I would really like Binomial[a,b] to be displayed as $a \choose b$, but still function as normal during calculation. I tried binom[a_, b_] := Binomial[a, b]//MatrixForm but that didn't work.

eg If I enter binom[a,b], I would like it to display as MatrixForm[{a,b}], but when I type in With[{a=10,b=5},binom[a,b]] I would like the output 252.

• Interpretation[ ]? – Dr. belisarius Jun 19 '15 at 12:58
• Are you aware of TraditionalForm? – Yves Klett Jun 19 '15 at 12:58
• @YvesKlett yes, but it doesn't evaluate the same, does it? – martin Jun 19 '15 at 12:58
• not foolprof, no, and just like MatrixForm an eternal source of confusion. – Yves Klett Jun 19 '15 at 12:59
• Check this tutorial. – Karsten 7. Jun 19 '15 at 13:06

$a \choose b$