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.
My work on innovation has focused on identifying the barriers to innovation in India, and seeking pathways at the level of both the nation and the firm to channelize our creative potential into a more systematic and sustainable innovation output. [Business Insider India]
A lawyer is arguing in a B.C. court this week that the RCMP systematically discriminated against women and a class action lawsuit against the federal government should go ahead. [CTV News]
As a plant systematist, Dr. Panero is interested in the distribution, diversity, and evolution of flowering plants, and his research focuses on the elucidation of phylogenetic relationships among Neotropical members of the sunflower family (Asteraceae) using traditional and molecular techniques. [Bio News Texas]