Question

I’ve got some question I cant solve:

#! /usr/bin/env python
import numpy as np
from scipy.interpolate import UnivariateSpline
from scipy.integrate import quad
import pylab as pl

x = ([0,10,20,30,40,50,60,70,...,4550,4560])
y = ([0,0,0,0,0,0,0,3,2,3,2,1,2,1,2,...,8,6,5,7,11,6,7,10,6,5,8,13,6,8,8,3])
s = UnivariateSpline(x, y, k=5, s=5)
xs = np.linspace(0, 4560, 4560)
ys = s(xs)

This is my code for making some Interpolation over some data.
In addition, I plotted this function.

But now I want to integrate it (from zero to infinity).

I tried

results = integrate.quad(ys, 0, 99999)

but it didnt work.

Can you give me some hints (or solutions) please? thanks

Answer 1

As Pierre GM said, you have to give a function for quad (I think also you can use np.inf for the upper bound, though here it doesn’t matter as the splines go to 0 quickly anyways). However, what you want is:

s.integral(0, np.inf)

Since this is a spline, the UnivariateSpline object already implements an integral that should be better and faster.