FeynCalc manual (development version)

Isolate

Isolate[expr] substitutes abbreviations KK[i] for all Plus[...] (sub-sums) in expr. The inserted KK[i] have head HoldForm. Isolate[expr, varlist] substitutes KK[i] for all subsums in expr which are free of any occurrence of a member of the list varlist. Instead of KK any other head or a list of names of the abbreviations may be specified with the option IsolateNames.

See also

Overview, IsolateNames, Collect2.

Examples

t0 = Isolate[a + b]

KK(19)\text{KK}(19)

t1 = Isolate[(a + b) f + (c + d) f + e, f]

e+f  KK(19)+f  KK(20)e+f \;\text{KK}(19)+f \;\text{KK}(20)

StandardForm[t1]

e+f  KK[19]+f  KK[20]e+f \;\text{KK}[19]+f \;\text{KK}[20]

{t0, t1, ReleaseHold[t1]}

{KK(19),e+f  KK(19)+f  KK(20),f(a+b)+f(c+d)+e}\{\text{KK}(19),e+f \;\text{KK}(19)+f \;\text{KK}(20),f (a+b)+f (c+d)+e\}

Isolate[a[z] (b + c (y + z)) + d[z] (y + z), {a, d}, IsolateNames -> fF]

fF(22)a(z)+fF(21)d(z)\text{fF}(22) a(z)+\text{fF}(21) d(z)

Information[fF]

0gi2hdxwlvyo6

Global`fF

fF\text{fF}

fF[26] = y + z

y+zy+z

fF[27] = b + c HoldForm[fF[26]]

b+c  fF(26)b+c \;\text{fF}(26)

Isolate[a - b - c - d - e, IsolateNames -> l, IsolateSplit -> 15]

l(24)l(24)

Clear[t0, t1, l, fF]