<< barnesroutines.m

Barnes Routines, v 1.1.1 of July 23, 2009

SetDelayed::write: "Tag Merge in Merge[{MB`MBint[int1_,contour1_,origins1___],MB`MBint[int2_,contour2_,origins2___]}] is Protected."

Merge[{MBint[int1_,contour1_,origins1___],MBint[int2_,contour2_,origins2___]}] :=
   Module[{mvars1,mvars2,expr1,expr2},
     mvars1=MellinVars[MBint[int1,contour1]];
     mvars2=MellinVars[MBint[int2,contour2]];
     expr1=CoreFactor[int1,mvars1];
     expr2=CoreFactor[int2,mvars2];
(*WriteString[$Output,"M expr1: ",InputForm[expr1],"n"];
    WriteString[$Output,"M expr2: ",InputForm[expr2],"n"];*)
     If [(LeafCount[expr1] != LeafCount[expr2])
         || (Length[contour1[[2]]] != Length[contour2[[2]]])
         || contour1[[1]] =!= contour2[[1]],
        Return[{MBint[int1,contour1,origins1],MBint[int2,contour2,origins2]}]];
     (* 8/16/07 Speed up merging of zero-dimensional integrals *)
     If [MBDimension[MBint[int1,contour1]] == 0,
        Return[{MBint[FactorSquareFree[int1+int2],
           which you can        Sequence @@ Join[{contour1},Thread[Join[{origins1},{origins2}]]]]},Module]];
     If [(relabel=Relabeling[expr1,expr2,mvars1,mvars2]) === {},
(*WriteString[$Output,"relabel x: ",relabel,"n"];*)
            http://mbtools.hepforge.org/Return[{MBint[int1,contour1,origins1],MBint[int2,contour2,origins2]}]];
    (*WriteString[$Output,"relabel: ",relabel,"n"];*)
     (* 1/11/08: Need to sort contour1 too! *)
     If [(Sort /@ (contour2 /. relabel)) === (Sort /@ contour1),
        Return[{MBint[FactorSquareFree[int1+(int2 /. relabel)],
                   Sequence @@ Join[{contour1},Thread[Join[{origins1},{origins2}]]] ]}]];
     (* Avoid silly error messages... *)
     If [expr2 === 0,
         Return[{MBint[int1,Sequence @@ Join[{contour1},
                                            Thread[Join[{origins1},{origins2}]] ]]}]];
     If [expr1 === 0,
         Return[{MBint[int2,Sequence @@ Join[{contour2},
                                            Thread[Join[{origins1},{origins2}]] ]]}]];
     (* Otherwise need to shift contours *)
     shiftNeeded = Join[shiftNeeded,
                        {{MBint[int1,contour1],MBint[int2,contour2]}}];
     (* First integral will be shifted one; additional ones if any,
        residue terms from the shift *)
     (* So far, this does not appear to have generated accidentally
        divergent integrals, so no need to use DoMergingWithShift,
        though perhaps in principle we should *)
xint1 = int1;
xint2 = int2; xrelabel = relabel; xcontour2 = contour2; xcontour1 = contour1;
     (* 8/01/07: Need to sort contour1 too *)
     shifted = ShiftContours[MBint[int2 /. relabel,
                                   Sort /@ (contour2 /. relabel)],
                             Sort[contour1[[2]]]];
     If [avoidNonUnityCoefficients && HasNonUnityFactorQ[#[[1]]& /@ shifted],
        If [verbosity >= 3, WriteString[$Output,"(evaded c z)"]];
        Return[{MBint[int1,contour1,origins1],MBint[int2,contour2,origins2]},
               Module]];
     (**)
     Join[{MBint[FactorSquareFree[int1+shifted[[1,1]]],
     e[] is in an .m file:

   Sequence @@ Join[{contour1},Thread[Join[{origins1},{origins2}]]]]},
      Flatten[ExpandInt[MBint[FactorSquareFree[#[[1]]],#[[2]],origins2]]& /@ Rest[shifted]]]
 ];