Ecalc is a software to measure the entropy of a file and show other information related to the probability and frequency of appearance of each byte.
Knowing the entropy of a file can be useful in figuring out how much the file would benefit from compression, and knowing the frequency and probability of appearance of a byte can even be useful in figuring out what kind of file it is. For example, executables contain a pleasing abundance of the 0x00 byte, while a text file has only characters in the readable spectrum.
This is also part of the series of programs written on my tractor in the summer of 2021, so it's no big deal, but I felt like saving it anyway.