My answer: it depends (how long the project might live? (a one of script vs. 10 years project that has to be maintained) What is the cost of adding a dependency

My answer: it depends (how long the project might live? (a one of script vs. 10 years project that has to be maintained) What is the cost of adding a dependency? (deployment, security risks, onboarding curve) Do ai need to care about numeric stability and such? etc. For example, for a one of script deployed in Pythonista on iOS, I would probably use a library if It is available/installable via pip with a single command, rolling out my own otherwise for 2x2 cases with a single google search unless I need to handle special cases.