Am doing a PhD in computer science. Can I publish my paper in an international journal of pure and applied mathematics?
Based on How good is the International Journal of Pure and Applied Mathematics? (http://www.ijpam.eu/) it does not sound like IJPAM is a good place to publish at all.
Also their website has a banner at the top that says "[2018-04-01] The journal stops consideration of any new submissions." And their "submission center" links are either broken or have no apparent way to actually submit a paper.
Their editorial board is listed only as "Hacked... Annon+". (!)
So I don't think you could publish your paper here even if you wanted to, which hopefully you don't anymore. This journal is no more, it has ceased to be, it's expired and gone to meet its maker, etc.
Look for a different journal for your paper, and be more choosy this time. Submitting to a predatory journal will only waste your money and not help your career.
The criteria for being accepted in any journal are based solely on the content of the submitted paper:
- relevance of the topic w.r.t the scope of the journal
- quality and originality of the contribution
- compliance with the editorial policy
The author's field of study is not relevant (and won't even be asked).
Publishing in mathematics journals is usually regarded as a strength in CS. However, if you plan to apply for academic positions in CS later, publishing only in mathematics journals might be an issue. Ideally, your publication record should reflect the profile you want to have depending on your target career.