A **<function_call>**
has a
lower precedence than an **<operand>**, but it has a
higher precedence than all the math, comparison, and logical
operations. This means you have to be careful about correctly
parenthesizing function arguments.

*
For example:*

sin x + 1

is evaluated as:

(sin x) + 1

In general, you have to put arguments that are expressions inside parentheses,

*
as in:*

sin (x + 1)

atan2 (y - 1) (z - 1)

This
rule has one exception, the unary minus. It is recognized as one
type of **<operand>**
you
don’t have to parenthesize.

*
For example:*

sin -x

is interpreted as:

sin (-x)