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FS98
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I understand what improper integrals are, but are they really integrals? The semantics are just a bit confusing.
An integral ##\int f(x)\,dx## is a solution to ##F(x)'=f(x)##.FS98 said:I understand what improper integrals are, but are they really integrals? The semantics are just a bit confusing.
Wouldn’t that definition of an integral rule out definite integrals as integrals?fresh_42 said:An integral ##\int f(x)\,dx## is a solution to ##F(x)'=f(x)##.
As long as there are no boundary conditions to this differential equation, many solutions are possible. Nevertheless, they still have to solve the equation. As such they are a kind of generic solution, the set of possible flows if you like, which we call improper integral (I think; here it is call undetermined). Fixing a boundary condition means to determine a single flow of the vector field, a single solution. So in a way, generic would be the better word, but that's semantics.
fresh_42 said:An integral ##\int f(x)\,dx## is a solution to ##F(x)'=f(x)##.
Maybe you're confusing the English terms "indefinite integral" and "improper integral."fresh_42 said:which we call improper integral (I think; here it is call undetermined).
Yes, I agree, and I agree with your definition of an improper integral.K Murty said:I do believe that is an indefinite integral.
Yes, I did. I couldn't imagine or have forgotten that there is a certain name for integrals with ##\pm \infty## as boundaries. And "undetermined" as literal translation is of course basically the same word as indefinite. Thanks.Mark44 said:Maybe you're confusing the English terms "indefinite integral" and "improper integral."
Yes they are integrals, just that they require limits to be solved. I suggest you google Riemann sum. I think the reason they are called improper is because the summation uses limits, I am not sure as to the why they are named so.FS98 said:I understand what improper integrals are, but are they really integrals? The semantics are just a bit confusing.
An improper integral is an integral that has one or both of its limits of integration as infinity or a point of discontinuity in the interval of integration. This means that the integral is not defined in the traditional sense and requires special techniques to evaluate.
An integral is improper if one or both of its limits of integration is infinity or if there is a point of discontinuity in the interval of integration. Additionally, if the function being integrated is not defined at one of the limits of integration, the integral is also considered improper.
A convergent improper integral is one that has a finite value when evaluated, while a divergent improper integral is one that does not have a finite value and therefore cannot be evaluated. This means that a convergent improper integral exists, while a divergent improper integral does not.
To evaluate an improper integral, you must first determine if it is convergent or divergent. If it is convergent, you can use special techniques such as the limit comparison test or the comparison test to find its value. If it is divergent, the integral cannot be evaluated and is considered to be undefined.
Improper integrals are important because they allow us to evaluate integrals that would otherwise be impossible to evaluate in the traditional sense. They also have many real-world applications, such as in physics and engineering, where they are used to solve problems involving infinite quantities or discontinuous functions.