At present, computer packages for working with classical
modular forms are available in Magma and in Sage, both based on
modular or Manin symbols. I will describe a new and extensive package
available in Pari/GP based on trace formulas, including in particular
modular forms of weight 1.
Links:
[1] https://www.mpim-bonn.mpg.de/taxonomy/term/39
[2] https://www.mpim-bonn.mpg.de/node/3444
[3] https://www.mpim-bonn.mpg.de/node/7239