The Split Is a Property of Parity, Not of Schur Complements

{"Building":[0],"Gram,":[1],"covariance,":[2],"kernel,":[3],"or":[4,9],"Toeplitz":[5],"matrices":[6],"from":[7,31,72],"exponentials":[8],"hyperbolic":[10],"functions?":[11],"You're":[12],"destroying":[13],"12":[14],"digits":[15],"before":[16],"you":[17,47,129],"factorise":[18],"anything.":[19],"One":[20],"line":[21,62],"fixes":[22],"it":[23,98,126,133],"—":[24],"34,000×":[25],"better.":[26],"When":[27],"your":[28,54,89],"entries":[29],"come":[30],"differences":[32],"of":[33,42,63,85],"large-argument":[34],"exponentials,":[35],"the":[36,45,51,57,67,79,95,108],"intermediate":[37],"products":[38],"run":[39],"13":[40],"orders":[41],"magnitude":[43],"above":[44],"values":[46],"actually":[48,118],"want,":[49],"and":[50,65,122,134],"subtraction":[52],"eats":[53],"precision.":[55],"Centring":[56],"argument":[58],"first":[59],"costs":[60],"one":[61,125],"code":[64],"cuts":[66],"worst":[68],"entry-wise":[69],"relative":[70],"error":[71],"240%":[73],"down":[74],"to":[75,131],"0.0073%.":[76],"Measured":[77],"against":[78],"largest":[80],"entry,":[81],"it's":[82],"a":[83],"factor":[84],"300":[86],"million.":[87],"If":[88],"matrix":[90],"is":[91,103,117,127],"\\"mysteriously\\"":[92],"indefinite":[93],"when":[94,130,135],"math":[96],"says":[97],"must":[99],"be":[100],"positive,":[101],"this":[102],"very":[104],"likely":[105],"why.":[106],"Separately:":[107],"block":[109],"structure":[110],"that":[111],"gets":[112],"blamed":[113],"on":[114],"Schur":[115],"complements":[116],"caused":[119],"by":[120],"parity,":[121],"knowing":[123],"which":[124],"tells":[128],"expect":[132],"not":[136],"to.":[137]}