Truncate series to the given degree.
Reduce the degree of the Legendre series to deg by discarding the high order terms. If deg is greater than the current degree a copy of the current series is returned. This can be useful in least squares where the coefficients of the high degree terms may be very small.
deg : non-negative int
The series is reduced to degree deg by discarding the high order terms. The value of deg must be a non-negative integer.
new_instance : Legendre
New instance of Legendre with reduced degree.
New in version 1.5.0.