If it happened in the past, use the past tense. Your studies were in the past. "In January, he died."
If it happened in the past and what is said is still valid, use the present. "In January we went (past) to Madrid, which is the capital of Spain." -> the present tense carries the nuance of "still is".
"In January we went (past) to Toledo, which was the capital of Spain." -> Toledo no longer is the capital of Spain,
I understand you examples. In my case, the experiment was done in the past, but if we would carry out today the same experiment, the results would be the same.
In the following examples:
In these studies the inputs are/were: the angle of... (the inputs were given in the past)
...the algorithm calculates/calculated the position of the... (The algorithm still calculates the same thing).
Therefore, in my opinion:
In these studies the inputs were: the angle of...
...the algorithm calculates the position of the...
I am changing my mind now that I have just had a quick look at some of the mathematics papers in your topic. They are not really what I thinking of as “experiments”. Here is a short extract and the past tense is not used:
However, this general procedure may be somewhat inefficient. It would be convenient to adapt it to the specific characteristics of the learning algorithm being used. We are going to do that for the case of the classical score + search learning algorithm based on local search , which uses the operators of arc insertion, arc deletion and arc reversal.
I am sorry we are not in a poisition to help you much here with this technical language. (I have a science degree but this maths is far too complicated for me! )
I suggest you derive your English style by reading some of these English language papers.