Trying to get the integral of a complex function

Question

I have a function in which I am trying to compute the definite integral. However, part of this function uses a map function within it and I am getting a TypeError: only size-1 arrays can be converted to Python scalars

Here is my function:

from scipy import integrate
import numpy as np
def func(a, b, c, d): #a is an array of 4000 elements, b is an array of ten elements, c&d are integers
    n = len(a)
    aver = a.mean()
    stdevn = a.std()
    final = []
    def fn(a=a, b=b, c=c, d=d):
        return ((1/n)*sum(map(lambda y: ((1/c) * np.exp(-0.5*((x - y - 0.2*((b-aver)/stdevn)*y)/bandwidth)**2)), a)))

    for i in b:
        total = integrate.quad(fn, a=0, b=100)
        final.append(total)
    return final

The result should be an array of length b (10). I am not sure where in the code I have the error. x is in the function as it is part of the integration

Traceback:

---> 10         total = integrate.quad(fn, a=0, b=100)                             
     11 
     12         final.append(total)

/opt/conda/lib/python3.7/site-packages/scipy/integrate/quadpack.py in quad(func, a, b, args, full_output, epsabs, epsrel, limit, points, weight, wvar, wopts, maxp1, limlst)
    350     if weight is None:
    351         retval = _quad(func, a, b, args, full_output, epsabs, epsrel, limit,
--> 352                        points)
    353     else:
    354         if points is not None:

/opt/conda/lib/python3.7/site-packages/scipy/integrate/quadpack.py in _quad(func, a, b, args, full_output, epsabs, epsrel, limit, points)
    461     if points is None:
    462         if infbounds == 0:
--> 463             return _quadpack._qagse(func,a,b,args,full_output,epsabs,epsrel,limit)
    464         else:
    465             return _quadpack._qagie(func,bound,infbounds,args,full_output,epsabs,epsrel,limit)

TypeError: only size-1 arrays can be converted to Python scalars

Asked By: GK89

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Source

Answer 1

I suppose you are using scipy.integrate.quad incorrectly. From the manual page it can be seen that the quad function needs the start and end of the interval as arguments. You try to pass two variables (I guess as arguments for your fn function?).
Try it similar to total = integrate.quad(fn, min_interval, max_interval, args=(a, b, c, d)).
Next time please add a minimal reproducible example. Like this it is more a guessing game.

Answered By: steTATO

Answer 2

This is a working solution:

from scipy import integrate
import numpy as np
def func(a, b, c, d): #a is an array of 4000 elements, b is an array of ten elements, c&d are integers
    n = len(a)
    aver = a.mean()
    stdevn = a.std()
    final = []
   

    for i in b:
        total = integrate.quad(lambda x: x*(inv*sum(map(lambda y: ((1/b) * np.exp(-0.5*((x-y-0.2*((b-aver)/stdevn*x/bandwidth))), clm))), a, b, epsabs = np.inf
        final.append(total)
    return final

Answered By: GK89

Trying to get the integral of a complex function

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