Calculating Singular Integrals

[martinjm97]

Hello,

I have had some trouble getting the library to fully evaluate some singular integrals. For example:

>>> N[Integral2[x/(1/2 - x), {x, -1, 1}]]
Integral2(x/(0.5 -1. x),{x,-1.,1.})

>>> N[Integral2[x/(1/2 - x)^2, {x, -1, 1}]]
Integral2(x/(0.5 -1. x)^2,{x,-1.,1.})

I'd expect a number as outputs for these examples rather than an expression.

I'm sorry if this is a simple problem. I am not an experienced user of Mathematica.

Answers to the provided questions:

• Mathematica version: 14.0.0 for Mac OS X x86 (64-bit) (December 13, 2023)
• FeynCalc version: 10.0.0
• I used the automatic installer.
• The output of Import[FileNameJoin[{$UserBaseDirectory, "Kernel", "init.m"}], "String"] is "( User Mathematica initialization file )"

Thank you!

[vsht]

Hi,

Integral{2,3,4,5} only contain some selected results results for calculations that Rolf was doing years ago. They are not universal functions capable of handling different integrals. If the expressions you are entering are not present there, they will simply remain unevaluated.

Cheers, Vlad

Am 30.04.24 um 16:52 schrieb Jesse Michel:

Hello,

I have had some trouble getting the library to fully evaluate some singular integrals. For example:

|>>> N[Integral2[x/(1/2 - x), {x, -1, 1}]] Integral2(x/(0.5 -1. x),{x,-1.,1.}) >>> N[Integral2[x/(1/2 - x)^2, {x, -1, 1}]] Integral2(x/(0.5 -1. x)^2,{x,-1.,1.}) |

I'd expect a number as outputs for these examples rather than an expression.

I'm sorry if this is a simple problem. I am not an experienced user of Mathematica.

Answers to the provided questions:

• Mathematica version: |14.0.0 for Mac OS X x86 (64-bit) (December 13, 2023)|
• FeynCalc version: 10.0.0
• I used the automatic installer.
• The output of Import[FileNameJoin[{$UserBaseDirectory, "Kernel", "init.m"}], "String"] is "( User Mathematica initialization file )"

Thank you!

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[martinjm97]

Thank you for the response! Are there other ways to calculate these sorts of integrals in FeynCalc?

--Jesse

[vsht]

If you know how to handle plus distributions by hand it shouldn't be difficult to cook something with Mathematica alone. I don't think that FeynCalc is even needed for that.

[martinjm97]

Got it. Thank you! I'll close off the issue.