# Comparison of STI and ROOT/TGeo volume weights

When STI creates an average volume, it does so by computing the weight of the volume analytically, then dividing it by the volume's capacity... (i.e. what high school geometry teachers would call volume).  This is done recursively to sum up the weights of all daughter volumes.  The analytic calculation does not correct for overlapping volumes.  So we need to know whether this is a problem or not.  ROOT can calculate the weight of a volume by sampling.  I setup the STI code to compute both the analytic and sampled weight of each volume, in grams.  Sampling is done to 1% accuracy.

List of volumes with > 5% error in weight
```StiMaker:INFO  - ISRL xxx Weight [STI] = 1.86778 [TGeo] 1.77436
StiMaker:INFO  - PSHA xxx Weight [STI] = 57.0807 [TGeo] 31.745
StiMaker:INFO  - PSHC xxx Weight [STI] = 33.9892 [TGeo] 31.7217
StiMaker:INFO  - PSHE xxx Weight [STI] = 41.4898 [TGeo] 38.1526
StiMaker:INFO  - PSHG xxx Weight [STI] = 41.4898 [TGeo] 38.1547
StiMaker:INFO  - PSMD xxx Weight [STI] = 76.7192 [TGeo] 44.8747
```
Small number of volumes with an error > 5%.  PSHA and PSMD are significantly (x2) larger than they should be... but this isn't enough of a difference to cause a problem.

Full List, for completeness.
```StiMaker:INFO  - ALCA xxx Weight [STI] = 2.96605 [TGeo] 2.96605
StiMaker:INFO  - APTS xxx Weight [STI] = 953.8 [TGeo] 953.126
StiMaker:INFO  - CFBK xxx Weight [STI] = 1.69376 [TGeo] 1.69376
StiMaker:INFO  - DRIV xxx Weight [STI] = 2.01515 [TGeo] 2.01515
StiMaker:INFO  - DTUH xxx Weight [STI] = 434.006 [TGeo] 430.819
StiMaker:INFO  - EFSA xxx Weight [STI] = 642.615 [TGeo] 643.762
StiMaker:INFO  - FGRL xxx Weight [STI] = 334.498 [TGeo] 333.745
StiMaker:INFO  - GLUA xxx Weight [STI] = 0.284801 [TGeo] 0.284801
StiMaker:INFO  - GLUB xxx Weight [STI] = 0.446706 [TGeo] 0.446706
StiMaker:INFO  - GLUC xxx Weight [STI] = 0.517031 [TGeo] 0.517031
StiMaker:INFO  - IBAP xxx Weight [STI] = 0.044744 [TGeo] 0.044744
StiMaker:INFO  - IBCW xxx Weight [STI] = 12.0473 [TGeo] 12.0456
StiMaker:INFO  - IBRB xxx Weight [STI] = 12.6299 [TGeo] 12.6299
StiMaker:INFO  - IBTS xxx Weight [STI] = 0.00369159 [TGeo] 0.00369159
StiMaker:INFO  - ICCA xxx Weight [STI] = 165.727 [TGeo] 165.689
StiMaker:INFO  - ICCD xxx Weight [STI] = 2.94753 [TGeo] 2.94753
StiMaker:INFO  - ICCL xxx Weight [STI] = 42.8398 [TGeo] 42.9843
StiMaker:INFO  - ICCT xxx Weight [STI] = 1248.49 [TGeo] 1248.62
StiMaker:INFO  - ICCU xxx Weight [STI] = 0.53974 [TGeo] 0.53974
StiMaker:INFO  - ICFC xxx Weight [STI] = 1.12446 [TGeo] 1.12446
StiMaker:INFO  - ICFD xxx Weight [STI] = 6.14068 [TGeo] 6.14068
StiMaker:INFO  - ICJA xxx Weight [STI] = 0.0467038 [TGeo] 0.0465153
StiMaker:INFO  - ICJS xxx Weight [STI] = 1.26515 [TGeo] 1.26027
StiMaker:INFO  - ICJU xxx Weight [STI] = 18.6352 [TGeo] 18.6358
StiMaker:INFO  - ICLE xxx Weight [STI] = 2.72361 [TGeo] 2.72478
StiMaker:INFO  - ICLN xxx Weight [STI] = 1.39002 [TGeo] 1.38584
StiMaker:INFO  - ICLP xxx Weight [STI] = 54.7604 [TGeo] 54.9291
StiMaker:INFO  - ICTA xxx Weight [STI] = 0.0550243 [TGeo] 0.0551005
StiMaker:INFO  - ICTB xxx Weight [STI] = 1.35872 [TGeo] 1.35696
StiMaker:INFO  - ICTC xxx Weight [STI] = 15.9384 [TGeo] 15.9777
StiMaker:INFO  - ICTE xxx Weight [STI] = 0.0467038 [TGeo] 0.0467768
StiMaker:INFO  - ICTJ xxx Weight [STI] = 18.8424 [TGeo] 18.8476
StiMaker:INFO  - ICTW xxx Weight [STI] = 0.0467038 [TGeo] 0.0466598
StiMaker:INFO  - IECE xxx Weight [STI] = 19.5741 [TGeo] 19.6074
StiMaker:INFO  - IECW xxx Weight [STI] = 10.1469 [TGeo] 10.1711
StiMaker:INFO  - IHBC xxx Weight [STI] = 1.82684 [TGeo] 1.82684
StiMaker:INFO  - IHBH xxx Weight [STI] = 6.72117 [TGeo] 6.72117
StiMaker:INFO  - IHTC xxx Weight [STI] = 1.82684 [TGeo] 1.82684
StiMaker:INFO  - IHTH xxx Weight [STI] = 6.72117 [TGeo] 6.72117
StiMaker:INFO  - IRSA xxx Weight [STI] = 1.14078 [TGeo] 1.14078
StiMaker:INFO  - IRSB xxx Weight [STI] = 1.14078 [TGeo] 1.14078
StiMaker:INFO  - IRSC xxx Weight [STI] = 1.14078 [TGeo] 1.14078
StiMaker:INFO  - ISBC xxx Weight [STI] = 1.33883 [TGeo] 1.33883
StiMaker:INFO  - ISBH xxx Weight [STI] = 6.9884 [TGeo] 6.9884
StiMaker:INFO  - ISCA xxx Weight [STI] = 17.7837 [TGeo] 17.8082
StiMaker:INFO  - ISCB xxx Weight [STI] = 20.374 [TGeo] 20.3748
StiMaker:INFO  - ISCC xxx Weight [STI] = 23.2179 [TGeo] 23.2241
StiMaker:INFO  - ISRB xxx Weight [STI] = 1.43334 [TGeo] 1.43334
StiMaker:INFO  - ISRC xxx Weight [STI] = 0.110591 [TGeo] 0.108428
StiMaker:INFO  - ISRL xxx Weight [STI] = 1.86778 [TGeo] 1.77436
StiMaker:INFO  - ISRO xxx Weight [STI] = 0.143999 [TGeo] 0.143999
StiMaker:INFO  - ISRR xxx Weight [STI] = 0.376782 [TGeo] 0.376782
StiMaker:INFO  - ISRS xxx Weight [STI] = 0.0418487 [TGeo] 0.0418487
StiMaker:INFO  - ISTC xxx Weight [STI] = 1.33883 [TGeo] 1.33883
StiMaker:INFO  - ISTH xxx Weight [STI] = 6.9884 [TGeo] 6.9884
StiMaker:INFO  - OSCA xxx Weight [STI] = 2699.39 [TGeo] 2694.53
StiMaker:INFO  - PBES xxx Weight [STI] = 216.447 [TGeo] 216.438
StiMaker:INFO  - PFLO xxx Weight [STI] = 925.804 [TGeo] 922.872
StiMaker:INFO  - PFLT xxx Weight [STI] = 1851.61 [TGeo] 1855.06
StiMaker:INFO  - PITN xxx Weight [STI] = 3419.53 [TGeo] 3442.24
StiMaker:INFO  - PRIS xxx Weight [STI] = 149.515 [TGeo] 149.278
StiMaker:INFO  - PRWS xxx Weight [STI] = 149.515 [TGeo] 148.442
StiMaker:INFO  - PSAB xxx Weight [STI] = 20.7775 [TGeo] 20.7775
StiMaker:INFO  - PSAE xxx Weight [STI] = 51.84 [TGeo] 51.84
StiMaker:INFO  - PSAK xxx Weight [STI] = 61.3742 [TGeo] 61.3751
StiMaker:INFO  - PSAL xxx Weight [STI] = 1095.49 [TGeo] 1099.91
StiMaker:INFO  - PSCK xxx Weight [STI] = 196.393 [TGeo] 196.393
StiMaker:INFO  - PSCL xxx Weight [STI] = 281.496 [TGeo] 281.496
StiMaker:INFO  - PSHA xxx Weight [STI] = 57.0807 [TGeo] 31.745
StiMaker:INFO  - PSHC xxx Weight [STI] = 33.9892 [TGeo] 31.7217
StiMaker:INFO  - PSHE xxx Weight [STI] = 41.4898 [TGeo] 38.1526
StiMaker:INFO  - PSHG xxx Weight [STI] = 41.4898 [TGeo] 38.1547
StiMaker:INFO  - PSMD xxx Weight [STI] = 76.7192 [TGeo] 44.8747
StiMaker:INFO  - PXIB xxx Weight [STI] = 1.81349 [TGeo] 1.81349
StiMaker:INFO  - PXLB xxx Weight [STI] = 4.97062 [TGeo] 4.97062
StiMaker:INFO  - PXRB xxx Weight [STI] = 5.33372 [TGeo] 5.33372
StiMaker:INFO  - PXTL xxx Weight [STI] = 1.44961 [TGeo] 1.44961
StiMaker:INFO  - PXTM xxx Weight [STI] = 1.49296 [TGeo] 1.49296
StiMaker:INFO  - PXTR xxx Weight [STI] = 1.37016 [TGeo] 1.37016
StiMaker:INFO  - SSCF xxx Weight [STI] = 131.302 [TGeo] 131.387
StiMaker:INFO  - SSCG xxx Weight [STI] = 486.613 [TGeo] 486.492
StiMaker:INFO  - SUCB xxx Weight [STI] = 127.857 [TGeo] 127.678
StiMaker:INFO  - SUCC xxx Weight [STI] = 3752.51 [TGeo] 3758.33
StiMaker:INFO  - SUCD xxx Weight [STI] = 474.773 [TGeo] 472.33
StiMaker:INFO  - SUCE xxx Weight [STI] = 6860.7 [TGeo] 6838.29
StiMaker:INFO  - SUCF xxx Weight [STI] = 560.861 [TGeo] 562.495
StiMaker:INFO  - SUCG xxx Weight [STI] = 1650.67 [TGeo] 1647.85
StiMaker:INFO  - TIFC xxx Weight [STI] = 64508.8 [TGeo] 64879.2
StiMaker:INFO  - TOFC xxx Weight [STI] = 1.43766e+06 [TGeo] 1.41928e+06

```

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