Résidu d’une expression en un point : residue

### 2.33.4 Résidu d’une expression en un point : `residue`

`residue` takes as argument an expression depending of a variable, this variable name and a complex a or an expression depending of a variable and the equality : variable_name=a. `residue` returns the residue of this exppression at the point a.
Input :

`residue(cos(x)/x```^```3,x,0)`

Or :

`residue(cos(x)/x```^```3,x=0)`

Output :

`(-1)/2`