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# "," operator in mathematics

Specify order of operations without backspacing to add parentheses
 (+8, -3) [vote for, against]

The "," enables last-minute modifications to a formula without you having to go back and put parentheses around the previous part of an expression.

For example, if you write "5.55 + 7.52 + 3.44" and then decide you want to divide this whole thing by two, just add ", /2" and the comma acts as if you had put the whole previous part of the expression in parentheses.

This would be great in spreadsheets, where backspacing in formulas is tedious, and where lots of parentheses make them hard to read (imagine an example much more complicated than the one above, like LEN(B4)/(ROUND(C6,2)*SUM(A1:A4)). The last thing you want is another set of parentheses. Its use also gives insight into the thought process of the author and helps the reader understand how to think about the formula.

The Comma can be easily integrated with the old mnemonic for order of operations. I suggest "Please Excuse My Dear Aunt Sally, Couldja?"

Thank you.

 — phundug, Sep 10 2006

Order of operations http://en.wikipedia...Order_of_operations
[ldischler, Sep 10 2006]

Reverse Polish notation http://en.wikipedia...rse_Polish_notation
[ldischler, Sep 10 2006]

If you wanted to then multiply that whole thing by 1.10, you'd type ", *1.10" and you could thus discard the curly braces.
 — phundug, Sep 10 2006

Would cause confusion for Europeans who use commas for decimal points.
 — AbsintheWithoutLeave, Sep 10 2006

I don't think so, because only a comma followed by an operator (+, -, x, /) is to be treated like this.
 — phundug, Sep 10 2006

I like the idea, though you'd have to make sure it ignores commas if they're within a function, so as not to potentially screw up some formulae, e.g. "SUM(A2:A5,C2:C8)".
 — imaginality, Sep 10 2006

)
 — spidermother, Sep 10 2006

 By the way, there are probably key strokes that jump you to the beginning and end of your text field. (Control-Leftarrow and Control-Rightarrow might work.)

 I don't see this as an operator as much as a detail of your input language, similar to Reverse Polish Notation. I love RPN for input, but wouldn't force it on the rest of the world as a reading format.

 The last thing I want in math is "insight into the thought process of the author". The thought process of the author was probably long and convoluted; what I want is to cut all that process and just get the end result.

(-) You must really like perl. (For its many ways of expressing the same thing.)
 — jutta, Sep 10 2006

If you want a compact formulation without all those parentheses, try APL.
 — ldischler, Sep 10 2006

//The last thing I want in math is "insight into the thought process of the author"//
But you already get that, [jutta]. You already see "6 + 7" as opposed to "7 + 6" depending on how the author wrote it. Some authors write (1/x)*5 when you may have preferred (5/x) since that's equivalent. Sounds to me like you're advocating that everyone use a canonical order of writing any mathematical expression, like the rules Maple or Mathematica might use.
 — phundug, Sep 10 2006

 > Sounds to me like you're advocating that everyone use a > canonical order of writing any mathematical expression, That's neither what I'm advocating nor what I wrote.

 Have what you write determined by the meaning you want to express, not by how you got there, or how you type it. That you don't know how to jump to the beginning of a text field in your software, or that you forgot a term and added it as an afterthought, doesn't help me understand the formula you're writing.

Thinking about BrauBeaton's example, is this "," just the same as a closing parentheses that doesn't have to be matched and implicitly extends to the beginning of the text? That might be a useful thing to do for a formula entry system - to implicitly match spurious closing parentheses at the beginning of the field.
 — jutta, Sep 10 2006

 "Would cause confusion for Europeans who use commas for decimal points."

 and to Americans who use commas for placeholders, i.e. 10000=10,000

(I've always preferred a space there to avoid confusion, i.e. 10000=10 000 )
 — kevinthenerd, Jun 10 2008

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