无法与 dblquad 集成

Question

所以我想集成一个带有常量的二重积分，比如 a、b 等，用户可以在其中分配这些常量的值：

积分的极限是x[0,1]和y[-1,2]

import numpy as np
import scipy.integrate as integrate

def g(y,x,a):
    return a*x*y

a = int(input('Insert a value --> '))
result = integrate.dblquad(g, 0, 1, lambda x: -1, lambda x: 2, args=(a))[0]
print(result)

但是我收到这个错误，我不明白为什么：

TypeError: integrate() argument after * must be an iterable, not int

我不明白。因为当我做同样的事情但是使用 quad() Python 时，它是正确的：

import numpy as np
import scipy.integrate as integrate

def g(x,a):
    return a*x

a = int(input('Insert a value --> '))
result = integrate.quad(g, 0, 1, args=(a))[0]
print(result)

结果：

0.5

Answer 1

这里的问题是您在可选参数 args 中提供的值是一个元组。在quad, it is what the function expects, but for dblquad, a sequence is required. Even though tuples are sequences (immutable ones), it seems that scipy makes a difference here and therefore it is why an error is raised. However it is misleading as a tuple is definitely an iterable的情况下。无论如何，这应该有效：

result = integrate.dblquad(g, 0, 1, lambda x: -1, lambda x: 2, args=[a])[0]

无法与 dblquad 集成

Can't integrate with dblquad

python

scipy

quad

python-3.6