Postfix Double Slash Notation with Multiple Parameters [duplicate]

Question

Examples

A convenient shorthand that I use frequently is the "double slash" notation to string commands together. For example, I can write:

x - 1 + x^2 //TraditionalForm

And receive back:

x^2 + x - 1

Or another example:

(x - 1)(x + 2) //Expand //TraditionalForm

Yields:

x^2 + x - 2

---

However, I have never been able to find a way to input multiple arguments into a function using this notation. That is, I cannot call something like:

x^2 + 9x + 5, 3 //PolynomialMod

Obviously the above can easily be written as:

PolynomialMod[x^2 + 9x + 5, 3]

(but what's the fun in that?)

Question

Is there a way to input multiple parameters using the shorthand postfix operator?

See also: http://reference.wolfram.com/language/ref/Postfix.html

Answer 1

A lot of functions in MMA have default values for Optional Arguments, for Example Flatten. It can take Flatten[expr] which means Flatten[expr, Infinity]

Some functions don't have such option and you need to feed the Optional Arguments but you can go around by building your own function

for your example, you can do this kind of trick like this:

f[expr_, n_: 3] := PolynomialMod[expr, n]

now

x^2 + 9 x + 5 // f
2 + x^2

In this case you will have fixed value for Optional Arguments which is 3 and if you need to use this method with other value than 3 you need to change 3 in the definition of f above. However, an easy way to do it is as follows:

x^2 + 9 x + 5 // PolynomialMod[#, 3] &

Answer 2

Algohi's answer is the most appropriate if one of the function's arguments is primary and the others secondary. However, you can get closer to the syntax that you suggested in your question using

{x^2 + 9 x + 5, 3} // Apply @ PolynomialMod

which works in version 10 using the operator form of Apply.

Or, to include earlier versions, you could define your own "postfix" operator like

Colon[list_, f_] := f @@ list

Then you can write

{x^2 + 9x + 5, 3} ∶ PolynomialMod

That's the \[Colon] character, also entered as Esc:Esc, or you could use any other infix operator with no built-in meaning.

Answer 3

You should use Sequence

PolynomialMod[x^2 + 9 x + 5, 3]

PolynomialMod@Sequence[x^2 + 9 x + 5, 3]

Sequence[x^2 + 9 x + 5, 3] // PolynomialMod
2 + x^2

all produce the same output.

Works with any function

Sequence[i, {i, 10}] // Table
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

Answer 4

You can do (but only for two arguments)

x^2 + 9x + 5 ~ PolynomialMod ~ 3

Answer 5

Sometimes you can use new Mathematica operator forms (V10+)

{-5, -3, -1, 2, 4, 6} // SortBy[Abs]

{-1, 2, -3, 4, -5, 6}