f maps elements from 3D real number space to 3D real number space.
Training examples are Identically Normally Distributed in R^3, as well as the testing.
The test is a sum of absolute errors (L1 norm).

## Marking scheme:
- <10 000 000 -> 50%
- <5 000 000 -> 60%
- <1 000 000 -> 70%
- <500 000 -> 80%
- <100 000 -> 90%
- <50 000 -> 100%