DiracDelta 没有给出正确的结果 [英] DiracDelta not giving correct result

问题描述

我必须在复杂的积分中使用 dirac delta 并希望看到它如何处理一个简单的案例，但它返回了错误的答案.任何线索我在下面做错了什么?

I have to use dirac delta in a complicated integral and was hoping to see how it works with a simple case but it returns the wrong answer. Any clue what I did wrong in the following?

from sympy import DiracDelta
from scipy import integrate

def f(x):
     return x*DiracDelta(x-1)

b, err = integrate.quad(f, 0, 5)    
print b

这会返回 0.0 而它不应该.

This returns 0.0 while it shouldn't.

推荐答案

看来 sympy 功能与 scipy 集成不兼容.一个需要使用 sympy 集成.以下给出正确答案

It seems sympy functions are not compatible with scipy integrate. One needs to use sympy integrate. The following gives the correct answer

from sympy import *
x = Symbol('x')
print integrate(x*DiracDelta(x-1), (x, 0, 5.0))    

虽然，我不确定 sympy.integrate 是否和 scipy.integrate 一样强大和通用.

Although, I am not sure if sympy.integrate is as powerful and versatile as scipy.integrate.

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