# Talk:Documentation/OOo3 User Guides/Calc Guide/Using functions

+ and * are not functions but operators. The umbrella term for 2+3 and sin(0.3) and PRODUCT(3;SUM(4;5)) is 'expression'.

SUM and + are not the same, and PRODUCT and * are not the same too. You see the difference, when you use ranges as parameter, or when you use them with empty cells or with cells, which contain text.

The terms 'function' and 'formula' are sometimes not clear, sometimes false. For example:

- "Like most functions, this one starts with an equal sign."

- Formulas start with an equal sign but functions never start with an equal sign, but simple start with their function name. (To please Excel users, entering formulas can also start with a + or a - sign and the equal sign will be added automatically.) Formulas are identified by starting with an equal sign. Formulas have the syntax =expression

- "Strictly speaking, when all the arguments are entered and a function is ready to run, it becomes a formula."

- Something like =7 is a formula although it doesn't contain any function. Functions are part of a formula, but the function alone is not a formula and will not become a formula.

- "because a formula can use functions as an argument."

- The term 'argument' is inapplicable to 'formula', but is a mathematical term in connection with functions.

"separated by semicolons, with no space between the arguments and the semicolons." That is wrong, you can use spaces if you want. White space is ignored.

"A formula, however, is limited by the fact that it can only do one function at a time." I do not understand that. What do you mean with "do one function at a time"?

Your description of nesting does not fit to the example =IF(A1<>0; A1*SIN(1/A1); 0).

Regina 22:32, 26 May 2009 (UTC)

The above issues have been dealt with, though there is still a bit of final editing to be done. --Kirk 05:53, 18 September 2009 (UTC)