Systematic vs. Systematical

Systematic is an adjective that describes something as being done in a certain way or according to a set of rules or procedures.
The adverb form for this word is systematically , the noun form is
systematicness, and a person who is known for being systematic or a scientist specialized in systemics is a systematist . Systemics is the science of categorizing or classifying things. Systematize is the verb to create a system or organize a chaotic process into something more orderly.

There are many more versions of the word system; however, none of them include systematical .  Some online dictionaries list the word as an adjective that is completely synonymous with systematic, but the most prominent dictionaries do not list it at all.