Starting with polynomial:
P : 1/40320*t^8 - 1/630*t^7 + 7/180*t^6 - 7/15*t^5 + 35/12*t^4 - 28/3*t^3 + 14*t^2 - 8*t + 1
Extension levels are: 8 15
-------------------------------------------------
Trying to find an order 15 Kronrod extension for:
P1 : 1/40320*t^8 - 1/630*t^7 + 7/180*t^6 - 7/15*t^5 + 35/12*t^4 - 28/3*t^3 + 14*t^2 - 8*t + 1
Solvable: 1
-------------------------------------------------
Ending with final polynomial:
P : 1/40320*t^23 - 1321458971878463728431158868211448749/140131152830662810231760351321960373120*t^22 + 113871244980250909905941313642883557769/70065576415331405115880175660980186560*t^21 - 80345375877803163060610066996383149249/476636574253955136842722283408028480*t^20 + 280844563176884013299687231953543657795/23831828712697756842136114170401424*t^19 - 14047034325612775419336962114804054457719/23831828712697756842136114170401424*t^18 + 260423314868753149611211114799838335738833/11915914356348878421068057085200712*t^17 - 7320023410165999821121062033256652878262551/11915914356348878421068057085200712*t^16 + 276841775271862841979273492511623546768160151/20852850123610537236869099899101246*t^15 - 1546376904377501519852879194031853141845284925/6950950041203512412289699966367082*t^14 + 1441128566016433858398261410015811805660397995/496496431514536600877835711883363*t^13 - 14645863887865592863408825396021425982640502305/496496431514536600877835711883363*t^12 + 115588099165521645425387145645829745857478740260/496496431514536600877835711883363*t^11 - 703798998621542164133228154543030150027328064820/496496431514536600877835711883363*t^10 + 3271612763428312963362077304873232331580821283000/496496431514536600877835711883363*t^9 - 11435488443061831970333746273288728594507090184200/496496431514536600877835711883363*t^8 + 29427441556725205882484968885114482849779153428800/496496431514536600877835711883363*t^7 - 54154583731401962247286958945527268814321893409600/496496431514536600877835711883363*t^6 + 68455807797807017866670233106175031786072731523200/496496431514536600877835711883363*t^5 - 56155486588075780950284407233779310060337995120000/496496431514536600877835711883363*t^4 + 27573272606112534018663738621163346115636307776000/496496431514536600877835711883363*t^3 - 7278695005170707842092158613933704312490636864000/496496431514536600877835711883363*t^2 + 926367569936047771524321550095925546976608128000/496496431514536600877835711883363*t - 44215032982302456894422836662435388543817856000/496496431514536600877835711883363
-------------------------------------------------
Computing nodes and weights
  current precision for roots: 53
  current precision for roots: 106
 current precision for weights: 53
Linear system for weights solvable: 0
  current precision for roots: 106
  current precision for roots: 212
 current precision for weights: 106
Linear system for weights solvable: 1
  current precision for roots: 212
  current precision for roots: 424
 current precision for weights: 212
Linear system for weights solvable: 1
Sufficient bits for target precision reached
-------------------------------------------------
The nodes are:
| (62.795637030796492686 + 6.6743680053248937008e-259j)  +/-  (1.76e-119, 1.76e-119j)
| (44.313644054556015408 + 2.4023175257703529039e-256j)  +/-  (9.5e-118, 9.5e-118j)
| (37.711336577684506976 - 4.6881607096628822046e-261j)  +/-  (2.49e-117, 2.49e-117j)
| (52.307514393675368771 + 9.0451105500970668035e-270j)  +/-  (1.88e-118, 1.88e-118j)
| (15.740678641278004578 - 2.337942667968159439e-280j)  +/-  (7.03e-117, 7.03e-117j)
| (4.2667001702876587936 + 2.1028514702433066786e-294j)  +/-  (1.47e-119, 1.47e-119j)
| (6.0347131949299002027 - 9.1691247257448224136e-292j)  +/-  (4.64e-118, 4.64e-118j)
| (19.07307159472004796 - 4.2220125674529006687e-304j)  +/-  (7.52e-117, 7.52e-117j)
| (9.5351318349218027687 + 5.5626636640775653308e-316j)  +/-  (5.48e-117, 5.48e-117j)
| (0.17027963230510099979 - 9.8095630571219616101e-331j)  +/-  (4.77e-125, 4.77e-125j)
| (0.90370177679937991219 - 3.8048878014266220312e-330j)  +/-  (1.11e-123, 1.11e-123j)
| (2.9129079659430103631 - 2.5180762643410876727e-328j)  +/-  (1.67e-120, 1.67e-120j)
| (27.166276952825258098 + 2.8937528944766232282e-324j)  +/-  (7.45e-117, 7.45e-117j)
| (32.07048246297504509 + 3.1177171991420600194e-336j)  +/-  (4.97e-117, 4.97e-117j)
| (12.859915370896654534 + 4.5633625914522611642e-348j)  +/-  (6.34e-117, 6.34e-117j)
| (1.7084153086780503284 - 3.5220014517037925027e-366j)  +/-  (5.84e-122, 5.84e-122j)
| (0.12846484527043087122 - 1.6234856728997554045e-369j)  +/-  (1.88e-125, 1.88e-125j)
| (10.758516010180995224 + 1.1421477017432629547e-359j)  +/-  (8.31e-117, 8.31e-117j)
| (22.863131736889264106 - 1.4649887671581215153e-370j)  +/-  (8.35e-117, 8.35e-117j)
| (0.28175899885837915012 - 6.5160803127714171792e-380j)  +/-  (7.22e-125, 7.22e-125j)
| (7.0459054023934656973 + 2.4438135430118975779e-371j)  +/-  (5.5e-117, 5.5e-117j)
| (2.2510866298661306893 - 5.8631741486227742116e-379j)  +/-  (4.58e-121, 4.58e-121j)
| (7.3247172264979703272 + 1.1589641171666904217e-373j)  +/-  (6.01e-117, 6.01e-117j)
-------------------------------------------------
The weights are:
| (6.760072913983544756e-27 + 1.7296112910624700744e-280j)  +/-  (3.45e-48, 6.43e-106j)
| (4.092993938729218285e-19 - 5.813038943531654854e-275j)  +/-  (3.24e-45, 6.02e-103j)
| (2.5443846853202832438e-16 + 7.203849769963840152e-274j)  +/-  (3.66e-44, 6.81e-102j)
| (1.7166885154960721982e-22 - 1.2995612304586590915e-277j)  +/-  (8.02e-47, 1.49e-104j)
| (4.5406031511837093827e-07 - 4.9780662462219633458e-268j)  +/-  (1.42e-38, 2.64e-96j)
| (0.021394120179552067697 + 3.1465377837948829557e-264j)  +/-  (1.31e-29, 2.44e-87j)
| (0.0055339014245900058886 - 3.4418288700422117732e-264j)  +/-  (3.59e-32, 6.67e-90j)
| (1.8512321161637316184e-08 + 3.7596928454567776886e-269j)  +/-  (2.7e-40, 5.02e-98j)
| (0.00011835880572998690021 + 2.505956308386096116e-265j)  +/-  (4.21e-36, 7.83e-94j)
| (-1.1621551579403677665 + 1.0904835893055503315e-262j)  +/-  (8.24e-29, 1.53e-86j)
| (0.28377225635029132095 + 1.1726445987325030483e-263j)  +/-  (7.51e-29, 1.4e-86j)
| (0.063114520670371561904 - 1.0109271126234948735e-263j)  +/-  (7.04e-30, 1.31e-87j)
| (7.2988940415124696313e-12 + 1.9461830490677079053e-271j)  +/-  (2.38e-43, 4.43e-101j)
| (6.1897519045146875392e-14 - 1.2040594240044796566e-272j)  +/-  (1.8e-44, 3.34e-102j)
| (6.8090247521271425381e-06 + 7.4404054923652142719e-267j)  +/-  (5.15e-39, 9.58e-97j)
| (0.15874957655826226288 - 1.738028588763588362e-263j)  +/-  (1.14e-32, 2.12e-90j)
| (0.94783942268562874266 - 6.6757797653183663845e-263j)  +/-  (3.38e-31, 6.29e-89j)
| (2.9047270778532951882e-05 - 8.2368412478321517057e-266j)  +/-  (3.93e-38, 7.31e-96j)
| (4.7478255853834863004e-10 - 2.8170198759057997012e-270j)  +/-  (1.11e-42, 2.07e-100j)
| (0.65839199759336591238 - 4.8288287270285548473e-263j)  +/-  (3.4e-33, 6.33e-91j)
| (-0.0036019833556331371175 + 8.4885491700371473421e-264j)  +/-  (2.99e-37, 5.57e-95j)
| (0.023271098166336991211 + 1.9708898143658385e-263j)  +/-  (2.19e-36, 4.3e-94j)
| (0.0035355595115615060454 - 6.3165239883646677265e-264j)  +/-  (2.13e-37, 3.96e-95j)
