# Function arg Compute the argument of a complex value. For a complex number `a + bi`, the argument is computed as `atan2(b, a)`. For matrices, the function is evaluated element wise. ## Syntax ```js math.arg(x) ``` ### Parameters Parameter | Type | Description --------- | ---- | ----------- `x` | number | BigNumber | Complex | Array | Matrix | A complex number or array with complex numbers ### Returns Type | Description ---- | ----------- number | BigNumber | Array | Matrix | The argument of x ### Throws Type | Description ---- | ----------- ## Examples ```js const a = math.complex(2, 2) math.arg(a) / math.pi // returns number 0.25 const b = math.complex('2 + 3i') math.arg(b) // returns number 0.982793723247329 math.atan2(3, 2) // returns number 0.982793723247329 ``` ## See also [re](re.md), [im](im.md), [conj](conj.md), [abs](abs.md)