let
  global rk108_step
  const a0100 = BigFloat(1//10)

  const a0200 = BigFloat("-0.915176561375291440520015019275342154318951387664369720564660")
  const a0201 = BigFloat("1.45453440217827322805250021715664459117622483736537873607016")

  const a0300 = BigFloat("0.202259190301118170324681949205488413821477543637878380814562")
  const a0302 = BigFloat("0.606777570903354510974045847616465241464432630913635142443687")

  const a0400 = BigFloat("0.184024714708643575149100693471120664216774047979591417844635")
  const a0402 = BigFloat("0.197966831227192369068141770510388793370637287463360401555746")
  const a0403 = BigFloat("-0.0729547847313632629185146671595558023015011608914382961421311")

  const a0500 = BigFloat("0.0879007340206681337319777094132125475918886824944548534041378")
  const a0503 = BigFloat("0.410459702520260645318174895920453426088035325902848695210406")
  const a0504 = BigFloat("0.482713753678866489204726942976896106809132737721421333413261")

  const a0600 = BigFloat("0.0859700504902460302188480225945808401411132615636600222593880")
  const a0603 = BigFloat("0.330885963040722183948884057658753173648240154838402033448632")
  const a0604 = BigFloat("0.489662957309450192844507011135898201178015478433790097210790")
  const a0605 = BigFloat("-0.0731856375070850736789057580558988816340355615025188195854775")

  const a0700 = BigFloat("0.120930449125333720660378854927668953958938996999703678812621")
  const a0704 = BigFloat("0.260124675758295622809007617838335174368108756484693361887839")
  const a0705 = BigFloat("0.0325402621549091330158899334391231259332716675992700000776101")
  const a0706 = BigFloat("-0.0595780211817361001560122202563305121444953672762930724538856")

  const a0800 = BigFloat("0.110854379580391483508936171010218441909425780168656559807038")
  const a0805 = BigFloat("-0.0605761488255005587620924953655516875526344415354339234619466")
  const a0806 = BigFloat("0.321763705601778390100898799049878904081404368603077129251110")
  const a0807 = BigFloat("0.510485725608063031577759012285123416744672137031752354067590")

  const a0900 = BigFloat("0.112054414752879004829715002761802363003717611158172229329393")
  const a0905 = BigFloat("-0.144942775902865915672349828340980777181668499748506838876185")
  const a0906 = BigFloat("-0.333269719096256706589705211415746871709467423992115497968724")
  const a0907 = BigFloat("0.499269229556880061353316843969978567860276816592673201240332")
  const a0908 = BigFloat("0.509504608929686104236098690045386253986643232352989602185060")

  const a1000 = BigFloat("0.113976783964185986138004186736901163890724752541486831640341")
  const a1005 = BigFloat("-0.0768813364203356938586214289120895270821349023390922987406384")
  const a1006 = BigFloat("0.239527360324390649107711455271882373019741311201004119339563")
  const a1007 = BigFloat("0.397774662368094639047830462488952104564716416343454639902613")
  const a1008 = BigFloat("0.0107558956873607455550609147441477450257136782823280838547024")
  const a1009 = BigFloat("-0.327769124164018874147061087350233395378262992392394071906457")

  const a1100 = BigFloat("0.0798314528280196046351426864486400322758737630423413945356284")
  const a1105 = BigFloat("-0.0520329686800603076514949887612959068721311443881683526937298")
  const a1106 = BigFloat("-0.0576954146168548881732784355283433509066159287152968723021864")
  const a1107 = BigFloat("0.194781915712104164976306262147382871156142921354409364738090")
  const a1108 = BigFloat("0.145384923188325069727524825977071194859203467568236523866582")
  const a1109 = BigFloat("-0.0782942710351670777553986729725692447252077047239160551335016")
  const a1110 = BigFloat("-0.114503299361098912184303164290554670970133218405658122674674")

  const a1200 = BigFloat("0.985115610164857280120041500306517278413646677314195559520529")
  const a1203 = BigFloat("0.330885963040722183948884057658753173648240154838402033448632")
  const a1204 = BigFloat("0.489662957309450192844507011135898201178015478433790097210790")
  const a1205 = BigFloat("-1.37896486574843567582112720930751902353904327148559471526397")
  const a1206 = BigFloat("-0.861164195027635666673916999665534573351026060987427093314412")
  const a1207 = BigFloat("5.78428813637537220022999785486578436006872789689499172601856")
  const a1208 = BigFloat("3.28807761985103566890460615937314805477268252903342356581925")
  const a1209 = BigFloat("-2.38633905093136384013422325215527866148401465975954104585807")
  const a1210 = BigFloat("-3.25479342483643918654589367587788726747711504674780680269911")
  const a1211 = BigFloat("-2.16343541686422982353954211300054820889678036420109999154887")

  const a1300 = BigFloat("0.895080295771632891049613132336585138148156279241561345991710")
  const a1302 = BigFloat("0.197966831227192369068141770510388793370637287463360401555746")
  const a1303 = BigFloat("-0.0729547847313632629185146671595558023015011608914382961421311")
  const a1305 = BigFloat("-0.851236239662007619739049371445966793289359722875702227166105")
  const a1306 = BigFloat("0.398320112318533301719718614174373643336480918103773904231856")
  const a1307 = BigFloat("3.63937263181035606029412920047090044132027387893977804176229")
  const a1308 = BigFloat("1.54822877039830322365301663075174564919981736348973496313065")
  const a1309 = BigFloat("-2.12221714704053716026062427460427261025318461146260124401561")
  const a1310 = BigFloat("-1.58350398545326172713384349625753212757269188934434237975291")
  const a1311 = BigFloat("-1.71561608285936264922031819751349098912615880827551992973034")
  const a1312 = BigFloat("-0.0244036405750127452135415444412216875465593598370910566069132")

  const a1400 = BigFloat("-0.915176561375291440520015019275342154318951387664369720564660")
  const a1401 = BigFloat("1.45453440217827322805250021715664459117622483736537873607016")
  const a1404 = BigFloat("-0.777333643644968233538931228575302137803351053629547286334469")
  const a1406 = BigFloat("-0.0910895662155176069593203555807484200111889091770101799647985")
  const a1412 = BigFloat("0.0910895662155176069593203555807484200111889091770101799647985")
  const a1413 = BigFloat("0.777333643644968233538931228575302137803351053629547286334469")

  const a1500 = BigFloat(1//10)
  const a1502 = BigFloat("-0.157178665799771163367058998273128921867183754126709419409654")
  const a1514 = BigFloat("0.157178665799771163367058998273128921867183754126709419409654")

  const a1600 = BigFloat("0.181781300700095283888472062582262379650443831463199521664945")
  const a1601 = BigFloat(27//40)
  const a1602 = BigFloat("0.342758159847189839942220553413850871742338734703958919937260")
  const a1604 = BigFloat("0.259111214548322744512977076191767379267783684543182428778156")
  const a1605 = BigFloat("-0.358278966717952089048961276721979397739750634673268802484271")
  const a1606 = BigFloat("-1.04594895940883306095050068756409905131588123172378489286080")
  const a1607 = BigFloat("0.930327845415626983292300564432428777137601651182965794680397")
  const a1608 = BigFloat("1.77950959431708102446142106794824453926275743243327790536000")
  const a1609 = BigFloat(1//10)
  const a1610 = BigFloat("-0.282547569539044081612477785222287276408489375976211189952877")
  const a1611 = BigFloat("-0.159327350119972549169261984373485859278031542127551931461821")
  const a1612 = BigFloat("-0.145515894647001510860991961081084111308650130578626404945571")
  const a1613 = BigFloat("-0.259111214548322744512977076191767379267783684543182428778156")
  const a1614 = BigFloat("-0.342758159847189839942220553413850871742338734703958919937260")
  const a1615 = BigFloat(-27//40)

  const b00 = BigFloat(1//30)
  const b01 = BigFloat(1//40)
  const b02 = BigFloat(1//30)
  const b04 = BigFloat(1//20)
  const b06 = BigFloat(1//25)
  const b08 = BigFloat("0.189237478148923490158306404106012326238162346948625830327194")
  const b09 = BigFloat("0.277429188517743176508360262560654340428504319718040836339472")
  const b10 = BigFloat("0.277429188517743176508360262560654340428504319718040836339472")
  const b11 = BigFloat("0.189237478148923490158306404106012326238162346948625830327194")
  const b12 = BigFloat(-1//25)
  const b13 = BigFloat(-1//20)
  const b14 = BigFloat(-1//30)
  const b15 = BigFloat(-1//40)
  const b16 = BigFloat(1//30)

  const c01 = BigFloat(1//10)
  const c02 = BigFloat("0.539357840802981787532485197881302436857273449701009015505500")
  const c03 = BigFloat("0.809036761204472681298727796821953655285910174551513523258250")
  const c04 = BigFloat("0.309036761204472681298727796821953655285910174551513523258250")
  const c05 = BigFloat("0.981074190219795268254879548310562080489056746118724882027805")
  const c06 = BigFloat(5//6)
  const c07 = BigFloat("0.354017365856802376329264185948796742115824053807373968324184")
  const c08 = BigFloat("0.882527661964732346425501486979669075182867844268052119663791")
  const c09 = BigFloat("0.642615758240322548157075497020439535959501736363212695909875")
  const c10 = BigFloat("0.357384241759677451842924502979560464040498263636787304090125")
  const c11 = BigFloat("0.117472338035267653574498513020330924817132155731947880336209")
  const c12 = BigFloat(5//6)
  const c13 = BigFloat("0.309036761204472681298727796821953655285910174551513523258250")
  const c14 = BigFloat("0.539357840802981787532485197881302436857273449701009015505500")
  const c15 = BigFloat(1//10)
  const c16 = BigFloat(1)

  function rk108_step(f, x, y, h)
    k00 = h*f(x,         y)
    k01 = h*f(x + c01*h, y + a0100*k00)
    k02 = h*f(x + c02*h, y + a0200*k00 + a0201*k01)
    k03 = h*f(x + c03*h, y + a0300*k00             + a0302*k02)
    k04 = h*f(x + c04*h, y + a0400*k00             + a0402*k02 + a0403*k03)
    k05 = h*f(x + c05*h, y + a0500*k00                         + a0503*k03 + a0504*k04)
    k06 = h*f(x + c06*h, y + a0600*k00                         + a0603*k03 + a0604*k04 + a0605*k05)
    k07 = h*f(x + c07*h, y + a0700*k00                                     + a0704*k04 + a0705*k05 + a0706*k06)
    k08 = h*f(x + c08*h, y + a0800*k00                                                 + a0805*k05 + a0806*k06 + a0807*k07)
    k09 = h*f(x + c09*h, y + a0900*k00                                                 + a0905*k05 + a0906*k06 + a0907*k07 + a0908*k08)
    k10 = h*f(x + c10*h, y + a1000*k00                                                 + a1005*k05 + a1006*k06 + a1007*k07 + a1008*k08 + a1009*k09)
    k11 = h*f(x + c11*h, y + a1100*k00                                                 + a1105*k05 + a1106*k06 + a1107*k07 + a1108*k08 + a1109*k09 + a1110*k10)
    k12 = h*f(x + c12*h, y + a1200*k00                         + a1203*k03 + a1204*k04 + a1205*k05 + a1206*k06 + a1207*k07 + a1208*k08 + a1209*k09 + a1210*k10 + a1211*k11)
    k13 = h*f(x + c13*h, y + a1300*k00             + a1302*k02 + a1303*k03             + a1305*k05 + a1306*k06 + a1307*k07 + a1308*k08 + a1309*k09 + a1310*k10 + a1311*k11 + a1312*k12)
    k14 = h*f(x + c14*h, y + a1400*k00 + a1401*k01                         + a1404*k04             + a1406*k06 +                                                             a1412*k12 + a1413*k13)
    k15 = h*f(x + c15*h, y + a1500*k00             + a1502*k02                                                                                                                                     + a1514*k14)
    k16 = h*f(x + c16*h, y + a1600*k00 + a1601*k01 + a1602*k02             + a1604*k04 + a1605*k05 + a1606*k06 + a1607*k07 + a1608*k08 + a1609*k09 + a1610*k10 + a1611*k11 + a1612*k12 + a1613*k13 + a1614*k14 + a1615*k15)

    # 10th order solution
    sol = y + b00*k00 + b01*k01 + b02*k02 + b04*k04 + b06*k06 + b08*k08 + b09*k09 + b10*k10 + b11*k11 + b12*k12 + b13*k13 + b14*k14 + b15*k15 + b16*k16
    # 8th order error estimate
    err = (k01 - k15) / 360
    return sol, err
  end
end