Starting with polynomial:
P : t^4 - 6*t^2 + 3
Extension levels are: 4 15
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Trying to find an order 15 Kronrod extension for:
P1 : t^4 - 6*t^2 + 3
Solvable: 1
-------------------------------------------------
Ending with final polynomial:
P : t^19 - 93567/667*t^17 + 56576166/7337*t^15 - 1577757510/7337*t^13 + 24226003620/7337*t^11 - 18992429820/667*t^9 + 3930143490/29*t^7 - 224016557310/667*t^5 + 250467132825/667*t^3 - 83438061525/667*t
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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
Positive weights:   19 out of 19
Indefinite weights: 0 out of 19
Negative weights:   0 out of 19
Extension rule has valid weights: 1
-------------------------------------------------
The nodes are:
| (-1.4697192347651409339 - 2.966374678358007194e-294j)  +/-  (1.14e-124, 1.14e-124j)
| (5.7525664932724817643 - 2.546839084350544192e-296j)  +/-  (2.49e-123, 2.49e-123j)
| (6.8956391981569169575 - 8.2025122720009471786e-303j)  +/-  (6.87e-124, 6.87e-124j)
| (-3.0954420462911432479 - 5.8057804840809850541e-310j)  +/-  (1.85e-123, 1.85e-123j)
| (3.0954420462911432479 + 2.1438496504343370045e-319j)  +/-  (1.74e-123, 1.74e-123j)
| (-4.7888356187420432164 + 2.9914130900544224354e-325j)  +/-  (3.2e-123, 3.2e-123j)
| (-6.8956391981569169575 - 3.7731028123742171212e-331j)  +/-  (7.1e-124, 7.1e-124j)
| (-5.7525664932724817643 + 3.9713069231901709564e-337j)  +/-  (2.68e-123, 2.68e-123j)
| (-2.3344142183389772393 + 2.2702258634222928314e-345j)  +/-  (1.12e-123, 1.12e-123j)
| (-3.9139822016309083791 + 3.068703025365229202e-356j)  +/-  (2.71e-123, 2.71e-123j)
| (0.74196378430272585765 - 2.9354937465622679588e-365j)  +/-  (3.92e-126, 3.92e-126j)
| (4.7888356187420432164 - 2.0177564282449440871e-371j)  +/-  (3.84e-123, 3.84e-123j)
| (-7.8180272582592220784e-377 - 1.8436842632235021138e-377j)  +/-  (1.53e-375, 1.53e-375j)
| (-1.9090466889022845717 + 1.9182376159440153141e-376j)  +/-  (5.87e-124, 5.87e-124j)
| (2.3344142183389772393 + 6.1899432312815284085e-375j)  +/-  (9.61e-124, 9.61e-124j)
| (1.4697192347651409339 - 1.1283750682023619495e-377j)  +/-  (1.03e-124, 1.03e-124j)
| (1.9090466889022845717 + 3.939303142368524409e-384j)  +/-  (5.42e-124, 5.42e-124j)
| (3.9139822016309083791 + 2.3175837650928006256e-392j)  +/-  (2.79e-123, 2.79e-123j)
| (-0.74196378430272585765 + 1.5087525712694703865e-397j)  +/-  (3.92e-126, 3.92e-126j)
-------------------------------------------------
The weights are:
| (0.093677240983887796956 + 2.6336273423598945133e-295j)  +/-  (3.22e-34, 5.15e-97j)
| (2.6754593145768840665e-08 - 1.1158111049009665785e-300j)  +/-  (3.33e-45, 5.33e-108j)
| (2.4680854113371119705e-11 + 1.9681320632704226826e-302j)  +/-  (1.21e-46, 1.94e-109j)
| (0.0026332912577838252915 - 7.6712068694957209211e-297j)  +/-  (1.14e-41, 1.82e-104j)
| (0.0026332912577838252915 + 2.7313940938367952548e-297j)  +/-  (5.92e-42, 9.47e-105j)
| (3.808387112574692344e-06 - 4.4288707915314437385e-299j)  +/-  (2.61e-45, 4.17e-108j)
| (2.4680854113371119705e-11 - 3.0325851794716792099e-302j)  +/-  (1.27e-48, 2.04e-111j)
| (2.6754593145768840665e-08 + 1.8854363760779289654e-300j)  +/-  (4.97e-47, 7.95e-110j)
| (0.018335754268755476046 + 1.1813682311670876364e-295j)  +/-  (1.36e-42, 2.18e-105j)
| (0.00015865791200224291336 + 6.4039772655200089941e-298j)  +/-  (9.88e-45, 1.58e-107j)
| (0.22434644523122326417 + 9.9068525398159959454e-296j)  +/-  (2.03e-41, 3.23e-104j)
| (3.808387112574692344e-06 + 2.3474255487115689753e-299j)  +/-  (1.06e-47, 1.69e-110j)
| (0.29618544838856196635 - 1.461650270848311223e-295j)  +/-  (1.05e-41, 1.66e-104j)
| (0.01275205098567983687 - 5.8563676961438794444e-295j)  +/-  (1.47e-42, 2.34e-105j)
| (0.018335754268755476046 - 2.6850215527354704216e-296j)  +/-  (4.76e-45, 7.59e-108j)
| (0.093677240983887796956 - 9.4530198399366175485e-296j)  +/-  (2.57e-44, 4.1e-107j)
| (0.01275205098567983687 + 7.6141995630626866804e-296j)  +/-  (8.62e-45, 1.37e-107j)
| (0.00015865791200224291336 - 2.9066995906917552457e-298j)  +/-  (1.74e-47, 2.83e-110j)
| (0.22434644523122326417 + 3.0108227272431918931e-295j)  +/-  (1.25e-44, 1.72e-107j)
