... LLCphysicalandtechnologicalinterestaswell;theclassofsurfacesforwhichana-lyticsolutionstothepotentialtheoryproblem(ofsolvingLaplace’sequation)canbefoundisthusconsiderablyenlarged,beyondthewell-establishedclassofsolutionsobtainedbyseparationofvariables(see,forexample[54]).Sinceitwillbecentraltolaterdevelopments,Sections1.1and1.2brieflydescribetheformofLaplace’sequationinsomeoftheseorthogonalcoordinatesys-tems,andthesolutionsgeneratedbytheclassicalmethodofseparationofvariables.TheformulationofpotentialtheoryforstructureswithedgesisexpoundedinSection1.3.Fortheclassofsurfacesdescribedabove,dual(ormultiple)seriesequationsarisenaturally,asdodual(ormultiple)integralequations.VariousmethodsforsolvingsuchdualseriesequationsaredescribedinSec-tion1.4,includingtheAbelintegraltransformmethodthatisthekeytoolemployedthroughoutthistext.ItexploitsfeaturesofAbel’sintegralequation(describedinSection1.5)andAbel-typeintegralrepresentationsofLegendrepolynomials,Jacobipolynomials,andrelatedhypergeometricfunctions(de-scribedinSection1.6).InthefinalSection(1.7),theequivalenceofthedualseriesapproachandthemoreusualintegralequationapproach(employingsingle-ordouble-layersurfacedensities)topotentialtheoryisdemonstrated.1.1Laplace’sequationincurvilinearcoordinatesThestudyofLaplace’sequationinvariouscoordinatesystemshasalonghistory,generating,amongstotheraspects,manyofthespecialfunctionsofappliedmathematicsandphysics(Besselfunctions,Legendrefunctions,etc.).Inthissectionwegathermaterialofareferencenature;foragreaterdepthofdetail,werefertheinterestedreadertooneofthenumeroustextswrittenonthesetopics,suchas[44],[32]or[74].HereweconsiderLaplace’sequationinthosecoordinatesystemsthatwillbeofconcreteinterestlaterinthisbook;inthesesystemsthemethodofseparationofvariablesisapplicable.Letu1,u2,andu3beasystemofcoor-dinatesinwhichthecoordinatesurfacesu1=constant,u2=constant,andu3=constantaremutuallyorthogonal(i.e.,intersectorthogonally).Fixapoint(u1,u2,u3)andconsidertheelementaryparallelepipedformedalongthecoordinatesurfaces,asshowninFigure1.1.Thus ... ob-tained by setting ξ = cosh α and η = cos β so that in terms of Cartesiancoordinatesx =d2sinh α sin β cos ϕ, y =d2sinh α sin β sin ϕ, z =d2cosh α cos β.The range of coordinates ... Press LLC1.1.2 Cylindrical polar coordinates In terms of Cartesian coordinates, the cylindrical coordinates arex = ρ cos φ, y = ρ sin φ, z = z,and the range of the coordinates is 0 ≤ ρ <...