Starting with polynomial:
P : t^6 - 15*t^4 + 45*t^2 - 15
Extension levels are: 6 13
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Trying to find an order 13 Kronrod extension for:
P1 : t^6 - 15*t^4 + 45*t^2 - 15
Solvable: 1
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Ending with final polynomial:
P : t^19 - 751/5*t^17 + 17731/2*t^15 - 3720303/14*t^13 + 61182771/14*t^11 - 557745045/14*t^9 + 2718773343/14*t^7 - 925925715/2*t^5 + 898474005/2*t^3 - 227548035/2*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:
| (4.1179938604202861108 - 1.3230374226932600172e-432j)  +/-  (4.2e-123, 4.2e-123j)
| (7.0765750832846489385 - 3.7118303734498590667e-442j)  +/-  (7.9e-124, 7.9e-124j)
| (-7.0765750832846489385 - 1.0546644721345894315e-447j)  +/-  (6.31e-124, 6.31e-124j)
| (-5.9322584888341448449 - 4.196761740327951025e-447j)  +/-  (2.92e-123, 2.92e-123j)
| (2.5825735544656472786 - 2.7826355017391849187e-448j)  +/-  (7.16e-124, 7.16e-124j)
| (5.9322584888341448449 - 1.9098140923914396244e-454j)  +/-  (2.61e-123, 2.61e-123j)
| (-4.9765807478085245814 + 4.7582213292782166041e-458j)  +/-  (4.33e-123, 4.33e-123j)
| (-1.2395478103514764889 + 2.0661221941097166825e-460j)  +/-  (1.7e-125, 1.7e-125j)
| (-4.1179938604202861108 + 1.4119830584981258312e-463j)  +/-  (4.29e-123, 4.29e-123j)
| (3.3242574335521189524 + 6.7737709495740433974e-465j)  +/-  (2.03e-123, 2.03e-123j)
| (0.61670659019259415219 - 1.8413937110723363896e-471j)  +/-  (1.67e-126, 1.67e-126j)
| (-2.5825735544656472786 + 6.0420731144561037784e-473j)  +/-  (7.96e-124, 7.96e-124j)
| (-1.8891758777537106755 - 9.8916800940537809695e-477j)  +/-  (1.38e-124, 1.38e-124j)
| (-7.0059170121911215167e-480 + 6.0725444407435082167e-480j)  +/-  (1.76e-478, 1.76e-478j)
| (4.9765807478085245814 - 4.90143135995080116e-489j)  +/-  (4.41e-123, 4.41e-123j)
| (1.2395478103514764889 + 7.159375734436683719e-494j)  +/-  (1.8e-125, 1.8e-125j)
| (1.8891758777537106755 + 3.365945343896710956e-495j)  +/-  (1.28e-124, 1.28e-124j)
| (-3.3242574335521189524 + 1.6503557127090002949e-497j)  +/-  (1.95e-123, 1.95e-123j)
| (-0.61670659019259415219 + 9.9253302111197588103e-501j)  +/-  (1.95e-126, 1.95e-126j)
-------------------------------------------------
The weights are:
| (6.8218868148789786659e-05 + 2.2112051415012464459e-436j)  +/-  (4.67e-48, 5.67e-110j)
| (7.0143362696332615191e-12 + 4.272115266226669438e-441j)  +/-  (2.03e-52, 2.47e-114j)
| (7.0143362696332615191e-12 - 1.1290653594703407855e-441j)  +/-  (2.63e-53, 3.2e-115j)
| (9.3282679543446881918e-09 + 5.880497096934480268e-440j)  +/-  (4.22e-52, 5.13e-114j)
| (0.010192871459860404338 + 1.4502414374651626751e-435j)  +/-  (4.62e-47, 5.62e-109j)
| (9.3282679543446881918e-09 - 3.257544618226265421e-439j)  +/-  (5.14e-52, 6.24e-114j)
| (1.5025302302015073817e-06 - 1.0853889064661036046e-438j)  +/-  (1.74e-51, 2.11e-113j)
| (0.11699153644968672284 + 2.7155330740892906063e-435j)  +/-  (1.72e-45, 2.09e-107j)
| (6.8218868148789786659e-05 + 1.0958748185870410956e-437j)  +/-  (6.67e-51, 8.11e-113j)
| (0.0012185284466662630536 - 6.7387486284228170731e-436j)  +/-  (5.74e-50, 7.06e-112j)
| (0.20364641663533098728 - 6.5159855201554151003e-435j)  +/-  (1.67e-46, 2.05e-108j)
| (0.010192871459860404338 + 3.3231964007612270743e-436j)  +/-  (1.51e-49, 1.85e-111j)
| (0.044872565218593958853 - 1.1158717004703985741e-435j)  +/-  (1.58e-48, 1.95e-110j)
| (0.24601670211240076346 + 6.4090293738241538188e-435j)  +/-  (2.81e-47, 3.5e-109j)
| (1.5025302302015073817e-06 + 1.1496973147155292395e-437j)  +/-  (2.3e-52, 2.87e-114j)
| (0.11699153644968672284 + 5.0543179721728674254e-435j)  +/-  (9.87e-49, 1.24e-110j)
| (0.044872565218593958853 - 3.0075272018090445397e-435j)  +/-  (2.84e-49, 3.54e-111j)
| (0.0012185284466662630536 - 7.187059461723117291e-437j)  +/-  (6.08e-51, 7.06e-113j)
| (0.20364641663533098728 - 4.8185386578689638577e-435j)  +/-  (1.4e-48, 1.72e-110j)
