Starting with polynomial:
P : 64*t^6 - 480*t^4 + 720*t^2 - 120
Extension levels are: 6 13
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Trying to find an order 13 Kronrod extension for:
P1 : 64*t^6 - 480*t^4 + 720*t^2 - 120
Solvable: 1
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Ending with final polynomial:
P : 64*t^19 - 24032/5*t^17 + 141848*t^15 - 14881212/7*t^13 + 122365542/7*t^11 - 557745045/7*t^9 + 2718773343/14*t^7 - 925925715/4*t^5 + 898474005/8*t^3 - 227548035/16*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: 1
  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:
| (2.3506049736744922228 - 1.0926683138147249489e-363j)  +/-  (1.5e-123, 1.5e-123j)
| (4.1947402052060847394 + 3.6648970503049998794e-380j)  +/-  (1.72e-123, 1.72e-123j)
| (-5.0038942289663325807 - 1.6035174158479917842e-391j)  +/-  (4.69e-124, 4.69e-124j)
| (-0.87649266230446559403 - 1.9518260956018036157e-393j)  +/-  (1.35e-125, 1.35e-125j)
| (1.8261552732757047254 - 4.8607775146781127383e-396j)  +/-  (5.12e-124, 5.12e-124j)
| (3.5189739938978274396 + 9.4129363995542637507e-409j)  +/-  (2.88e-123, 2.88e-123j)
| (-1.8261552732757047254 - 9.4624322866624222415e-415j)  +/-  (5.12e-124, 5.12e-124j)
| (-4.1947402052060847394 - 2.8422825391726925381e-415j)  +/-  (2.11e-123, 2.11e-123j)
| (-3.5189739938978274396 - 6.7482941037642311714e-421j)  +/-  (2.92e-123, 2.92e-123j)
| (1.1288011975060808936e-426 + 1.6493099558026587484e-428j)  +/-  (2.14e-425, 2.14e-425j)
| (1.3358490740136969497 - 3.6520434735630300858e-429j)  +/-  (1.06e-124, 1.06e-124j)
| (5.0038942289663325807 + 5.6375787888320989548e-436j)  +/-  (4.9e-124, 4.9e-124j)
| (-0.43607741192761650868 - 3.307194225699828119e-445j)  +/-  (9.41e-127, 9.41e-127j)
| (-2.911861383587753379 - 1.284574028343859792e-446j)  +/-  (3.04e-123, 3.04e-123j)
| (2.911861383587753379 + 2.0881794176489544868e-454j)  +/-  (3.01e-123, 3.01e-123j)
| (0.87649266230446559403 + 4.6512383103467674439e-463j)  +/-  (1.35e-125, 1.35e-125j)
| (0.43607741192761650868 - 5.6519838353081363974e-464j)  +/-  (1.35e-126, 1.35e-126j)
| (-2.3506049736744922228 + 3.6302347788072331269e-463j)  +/-  (1.49e-123, 1.49e-123j)
| (-1.3358490740136969497 - 1.6059368103122671463e-471j)  +/-  (1.03e-124, 1.03e-124j)
-------------------------------------------------
The weights are:
| (0.0012185284466662630536 + 3.9981284306135151839e-366j)  +/-  (2.04e-47, 5.59e-109j)
| (9.3282679543446881918e-09 + 7.9774978289943039382e-370j)  +/-  (3.03e-52, 8.3e-114j)
| (7.0143362696332615191e-12 + 4.278010109496065927e-372j)  +/-  (8.24e-55, 2.26e-116j)
| (0.11699153644968672284 - 1.1222174109124435703e-365j)  +/-  (7.99e-47, 2.18e-108j)
| (0.010192871459860404338 - 1.0568958714770247448e-365j)  +/-  (6.98e-47, 1.91e-108j)
| (1.5025302302015073817e-06 - 2.1030819150912003289e-368j)  +/-  (5.91e-51, 1.62e-112j)
| (0.010192871459860404338 - 1.3270781428107436641e-366j)  +/-  (8.88e-49, 2.43e-110j)
| (9.3282679543446881918e-09 - 2.2476407895773112228e-370j)  +/-  (6.04e-54, 1.65e-115j)
| (1.5025302302015073817e-06 + 4.1862896302438171267e-369j)  +/-  (4.44e-53, 1.21e-114j)
| (0.24601670211240076346 - 2.7949031253718547613e-365j)  +/-  (5.29e-48, 1.43e-109j)
| (0.044872565218593958853 + 1.6443377810123301763e-365j)  +/-  (1.4e-48, 3.8e-110j)
| (7.0143362696332615191e-12 - 1.1857969076092146821e-371j)  +/-  (7.59e-56, 2.07e-117j)
| (0.20364641663533098728 + 2.0379279990891981466e-365j)  +/-  (1.81e-48, 4.87e-110j)
| (6.8218868148789786659e-05 - 4.2692910107063597259e-368j)  +/-  (1.58e-52, 4.33e-114j)
| (6.8218868148789786659e-05 + 4.0029832918391950433e-367j)  +/-  (5.66e-52, 1.52e-113j)
| (0.11699153644968672284 - 2.4567362512861582847e-365j)  +/-  (1.99e-49, 5.38e-111j)
| (0.20364641663533098728 + 2.9662973632019514707e-365j)  +/-  (3.1e-49, 8.29e-111j)
| (0.0012185284466662630536 + 2.8321377646724877242e-367j)  +/-  (6.01e-52, 1.7e-113j)
| (0.044872565218593958853 + 4.5263047978688325584e-366j)  +/-  (1.53e-50, 3.64e-112j)
