A soft question, when I was in high school and in University I took scientific writing classes and people told me I should use passive voice as much as possible to sound objective, but when I entered grad school people told me I should not use passive voice unless I work in Chemistry. So Which one should I follow?
In computer science how is using passive voice regarded?
research
The bottom line advice is: Use whichever voice best aids understanding.Many people over-use the passive voice, thinking that it makes them sound more scientific.  In practice, it's more common for the passive voice to make sentences harder to follow.Therefore, as a rough guideline, it's helpful to use the following principle: use the active voice whereever possible.  If you find yourself writing in passive voice, check whether your sentence would be clearer, simpler, or easier to understand if written in the active voice.I recommend you read style guides on clear writing.  You'll find they tend to warn against over-use of passive voice: active voice often makes sentences simpler, more direct, more forceful, more vivid, and thus both more concise and more memorable.  Strunk & White have some good examples of this guideline; see, e.g., Rule 11 and Rule 12.There are some special cases where there are conventions or norms within the field that are worth following.  See, e.g.,Use of I, we and the passive voice in a scientific thesisIs it recommended to use we in research papers?.