In[]:=
$Version
Out[]=
14.2.0 for Microsoft Windows (64-bit) (December 26, 2024)
Using:
ArcTan[x]==InverseMellinTransform
1-2s
x
Gamma
1
2
-sGamma[1-s]Gamma[s]
2Gamma
3
2
-s
,s,1
then:
In[]:=
Integrate
1-2s
x
Gamma
1
2
-sGamma[1-s]Gamma[s]
2Gamma
3
2
-s
*
1
x^2-x+1
,{x,0,Infinity}
Out[]=
2
π
Csc[πs]Csc[2πs]3Cos
4πs
3
+
3
Sin
4πs
3

3(1-2s)
if 0<Re[s]<1
If:
2
π
Csc[πs]Csc[2πs]3Cos
4πs
3
+
3
Sin
4πs
3

3(1-2s)
=
π
2
Gamma[1-2s]
Gamma[1-s]Gamma[s]Gamma[2s]
3
Gamma[2-2s]Gamma1-
4s
3
Gamma
4s
3

+
π
2
Gamma[1-2s]
Gamma[1-s]Gamma[s]Gamma[2s]
Gamma[2-2s]Gamma
1
2
-
4s
3
Gamma
1
2
+
4s
3

then:
In[]:=
1/(2PiI)NContourIntegrate
π
2
Gamma[1-2s]
Gamma[1-s]Gamma[s]Gamma[2s]
3
Gamma[2-2s]Gamma1-
4s
3
Gamma
4s
3

,s∈InfiniteLine
1
4
,0,{0,1}+1/(2PiI)NContourIntegrate
π
2
Gamma[1-2s]
Gamma[1-s]Gamma[s]Gamma[2s]
Gamma[2-2s]Gamma
1
2
-
4s
3
Gamma
1
2
+
4s
3

,s∈InfiniteLine
3
16
,0,{0,1}(*NumericisOK*)
Out[]=
1.89941+0.
In[]:=
A=System`MeijerGDump`FromSlaterForm
π
2
Gamma[1-2s]
Gamma[1-s]Gamma[s]Gamma[2s]
3
Gamma[2-2s]Gamma1-
4s
3
Gamma
4s
3

,s//ReleaseHold+System`MeijerGDump`FromSlaterForm
π
2
Gamma[1-2s]
Gamma[1-s]Gamma[s]Gamma[2s]
Gamma[2-2s]Gamma
1
2
-
4s
3
Gamma
1
2
+
4s
3

,s//ReleaseHold
Out[]=
MeijerG0,
1
6
,
1
3
,
1
3
,
2
3
,
2
3
,
5
6
,
5
6
,
1
4
,
3
4
,0,
1
6
,
1
3
,
1
3
,
2
3
,
2
3
,
5
6
,-
1
6
,
1
4
,
3
4
,1,
1
3

32
3
3
π
+
MeijerG0,0,
1
6
,
1
3
,
1
3
,
1
2
,
2
3
,
2
3
,
5
6
,
5
6
,
1
8
,
3
8
,
5
8
,
7
8
,0,0,
1
6
,
1
3
,
1
3
,
1
2
,
2
3
,
2
3
,
5
6
,-
1
6
,
1
8
,
3
8
,
5
8
,
7
8
,1,
1
3

32
3
π
A//FunctionExpand//FullSimplify(*ClosedformisOK*)
Out[]=
2
π
3
3
In[]:=
%//N
Out[]=
1.89941