LaTex / MikTex is open source. It is a writer’s publishing tool.
I was introduced to this software by Dr Genick Bar-Meir. He is the owner of The Potto Project. Please see this link www.potto.org. Dr Genick wrote books on fluid mechanics and compressible flow. He offers them as free textbooks. I worked with him on his English grammar because English is his third or fourth language.
My initial opinion of LaTex / MikTex is that it is not easy to use but I changed my opinion after using it. At the time, I was using Microsoft products and Adobe software for publishing. I never heard of LaTex before. It dawned on me that here was another software which is a great layout tool and also it is so much better when there are mathematical formulas. I found that typing in a formula can be daunting initially but after getting used to it, it is so much easier than Microsoft Word. Of course, at that time, the formulas were already created by Dr Genick. All I had to do was to check on the grammar and leave his formulas alone!
A sample of a formula for Introduction to Thermodynamics:
In mechanics, the work was defined as