[Mathematica Help] An integration involving many vector variables

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SUMMARY

The discussion centers on integrating a complex function involving multiple vector variables in Mathematica. The user successfully computes a one-dimensional integral but encounters errors when attempting to perform a two-dimensional integration with vector variables. Specifically, the error "Integrate::ilim: Invalid integration variable or limit(s) in {kx,ky}" indicates a misunderstanding of how to define integration variables in Mathematica for vector functions. The user seeks clarification on the correct approach to integrate such functions involving vectors and complex numbers.

PREREQUISITES
  • Understanding of vector calculus and integration techniques.
  • Familiarity with Mathematica syntax and functions, particularly the Integrate function.
  • Knowledge of complex analysis, especially dealing with complex conjugates.
  • Basic understanding of how to define and manipulate lists in Mathematica.
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  • Learn how to define integration variables for multi-dimensional integrals in Mathematica.
  • Research the use of the Integrate function with vector-valued functions in Mathematica.
  • Explore examples of integrating complex functions involving multiple variables in Mathematica.
  • Study the implications of complex conjugates in integration and their treatment in Mathematica.
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This discussion is beneficial for mathematicians, physicists, and engineers who use Mathematica for complex integrations, particularly those dealing with vector variables and complex functions.

elduderino
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I have an expression which has six terms. I am posting one of the terms, in its basic form:

<br /> f1= \int \frac{d\vec{k}}{( \xi [\vec{k}] + i d - \xi [\vec{k}-\vec{b}] ) ( \xi [\vec{k}] + i c + i d - \xi [\vec{k}-\vec{a} - \vec{b}]) }<br />

Then there are f2, f3,f4..f6. They are all complex conjugates.

The six terms together constitute the expression F(\vec{a},\vec{b},c,d,\vec{k}). I am to integrate and hence evaluate and visualize the function F(\vec{a},\vec{b},c,d,\vec{k}) in Mathematica. I was able to do the one-dimensional case correctly, where all the variables can be treated as scalars. However I am having trouble doing the 2-D case.

In fact, I am a little unsure about how the math works when vectors are involved, and also how to make mathematica evaluate this integration for me. Here is what I tried.

I declared
k={kx,ky} ... a={ax,ay} ... etc

The function F(\vec{a},\vec{b},c,d,\vec{k}) now becomes a list as:

F(\vec{a},\vec{b},c,d,\vec{k}) = \{ F(ax,bx,c,d,kx) , F(ay,by,c,d,ky) \}


Now if I use: Integrate[F, k]
I should expect an output of the form {Expr1,Expr2}
However, I get an error... "Integrate::ilim: Invalid integration variable or limit(s) in {kx,ky}."

Can somebody explain what I am doing wrong here?

Even more fundamentally, I somehow doubt if this approach to carrying out the integration is correct. Can someone hint how such integrations involving vector variables and complexes (iotas) are solved?
 
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If I define:
f[t_] := {t, Sqrt[t + 1], -Exp[t]}
and then compute
Integrate[f[t], t]
I get the expected result
{t^2/2, 2/3 (1 + t)^(3/2), -E^t}

So Mathematica can evaluate the integral of vector valued functions. Are you perhaps trying to integrate over a surface or a field where the function is not just vector valued but also takes vector arguments?
 

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