; TeX output 1997.01.23:0049soRDtGGcmr17The7tGGcmss17delaqrrayq:package!", cmsy10XQ cmr12DarvidCarlislepScarlisle@cs.man.ac.uk&37 1994/03/149VINff cmbx121aLExamplesIK`y cmr10The=additionto cmmi10aCbc_d џ^_XSimilarlyifanenvironmentequivqalentto- cmcsc10PlainTU>'ExX's\casescouldbGede nedIby:I\begin{array}\{{lL}.UU...8a͍f(x)=^dG0=ÐifUUx=0Gsin8(x)=x=ÐotherwiseSIHereBL2issuppGosedtodenoteacolumnofleftalignedL-Rtext.\ItmaybGede nedIvia:Q\newcolumntype{L}{>{$}l<{$}},:as?discussedinarray.sty.NotethatasIthedelimitersmustalwaysbGeusedinpairs,the`.'mustbGeusedtodenotea`nullIdelimiter'.XThisfeatureisespGeciallyusefulifthe[t]or[b]argumentsarealsoused.IInthesecasestheresultisnotequivqalenttosurroundingtheenvironmentbyI\left...\right,UUascanbGeseenfromthefollowingexample:-m0 m@\n1\n2\n3\o1 \oAZ0 @d123Z1 A0 @ձIJ1ձ2ձ3߱ū1 ߱AqDznotR :0 :B :B :B :Bfi :@N;1N;2N;3R$N<1$NmacrotestsforanoptionaldelimiterbGeforetheleftbraceofthemainpream-Ible7,argument.gIfthereisnodelimiter,=5\@arrayleftand\@arrayrightaremadeIano-ops,and\@arrayiscalledwiththepGositionalargument.cFOtherwisecallI\@del@array.Ls4S\def\@@array[#1]{\@ifnextchar\bgroup Ls5]{\let\@arrayleft\relax\let\@arrayright\relax\@array[#1]}%Ls6]{\@del@array[#1]}} L\@del@arrayIW*eUUnowknowthatwehaveanarray(ortabular)withdelimiters.Ls7S\def\@del@array[#1]#2#3#4{%IThefollowinglineiscompletelyredundantbutitdoGescatcherrorsinvolvingde- IlimitersbGeforetheprocessingofthealignmentbegins.%AcommonerrorislikelyItoحbGeomitingthe`.'ina\cases-typeconstruction.Thiscausesthe rsttokenIof)nthealignmenttobGegobbled,26possiblycausinglotsofspuriouserrorsbeforetheIcauses|oftheerror,{themissingdelimiter,isdiscovereds|as\@arrayrightputstheIalignmentUUandthedelimiterstogether.Ls8]\setbox\z@\hbox{$\left#2\right#4$}%IInҥthecaseofa`c'argumentwedonotneedtorebGoxthealignment,sowecanIde neUU\@arrayleftand\@arrayrightjusttoinsertthedelimiters.Ls9]\if#1c\def\@arrayleft{\left#2}\def\@arrayright{\right#4}%IOtherwisewe(should)havea[t]?or[b]argument, so rstwestorethealign-Iment,UUwithoutdelimitersinbGox0.I10]\else\def\@arrayleft{\setbox\z@}%IThenUUafterthealignmentis nished:I11]\def\@arrayright{%ICalculatetheamountthebGoxneedstobGelowered(thiswillbGenegativeinthe Icaseh[of[b]).AhVlittlebitofarithmeticcf.theTU>'ExXBoGok,mAppendixh[G,rule8.W*eIcalculateKtheamountthisway*,M ratherthanjusttakingthedi erencebGetweentheIdepthofbGox0andthedepthoftheboxde nedbelow,̑asthedepthofthatboxImay?bGea ectedbythedelimitersif\delimitershortfallor\delimiterfactorIhaveUUnon-standardvqalues.I12kJ\dimen@=\dp\z@ I13kJ\advance\dimen@-\ht\z@I14kJ\divide\dimen@by\tw@I15kJ\advance\dimen@by\fontdimen22\textfont\tw@INowUUlowerthealignmentandthedelimitersintoplace.I16kJ\lower\dimen@\hbox{$\left#2\vcenter{\unvbox\z@}\right#4$}}%IEndUUthe\if#1cI17]\fi2 soINowUUthatwehavede ned\@arrayleftand\@arrayright,call\@array.I18]\@array[#1]{#3}}I19Sh!5" cmmi9=pack9age#g i6I&N cmbx122.1gnewarray.styuTIAllthefeaturesoftheoldnewarraystyleoptionhavebGeenmergedintothearray IorUUdelarrayoptions.3;&N cmbx12#ow cmss9" cmsy9!5" cmmi9ߤN cmtt9- cmcsc10 cmmi10K`y cmr10ٓRcmr7u cmex10