Truncated log10 transform.
- x : num | num iterable
- values to be transformed.
- th : num
- values below th are transormed to 0.
Must be positive.
- r : num (default = 10**4)
- maximal transformed value.
- d : num (default = log10(2**18))
- log10 of maximal possible measured value.
tlog(10**d) = r
Array of transformed values.
