### 2.24.21 Truncate of order *n* : `truncate`

`truncate` takes as argument, a polynomial and an integer
`n`.

`truncate` truncates this polynomial at order `n` (removing
all terms of order greater or equal to `n+1`).

`truncate` may be used to transform a series expansion into a
polynomial or to compute series expansion step by step.

Input :

`truncate((1+x+x``^`

`2/2)``^`

`3,4)`

Output :

`(9*x``^`

`4+16*x``^`

`3+18*x``^`

`2+12*x+4)/4`

Input :

`truncate(series(sin(x)),4)`

Output :

`(-x``^`

`3-(-6)*x)/6`

Note that the returned polynomial is normalized.