Top Journals and Conferences

Numerical linear algebra:

• SISC (journal): SIAM Journal on Scientific Computing
• SIMAX (journal): SIAM Journal on Matrix Analysis and Applications
• SINUM (journal): SIAM Journal on Numerical Analysis
• TOMS (journal): ACM Transactions on Mathematical Software

Data mining, machine learning, etc:

• JMLR (journal): Journal of Machine Learning Research
• TKDE (journal): IEEE Transactions on Knowledge and Data Engineering
• ICML (conference): International Conference on Machine Learning
• NIPS (conference): Annual Conference on Neural Information Processing Systems
• SIGKDD (conference): ACM SIGKDD International Conference on Knowledge Discovery & Data Mining

Computer vision:

• IJCV (journal): International Journal of Computer Vision
• PAMI (journal): IEEE Transactions on Pattern Analysis and Machine Intelligence

Not an official list. More on this later..

References:

• Some journals in Numerical Linear Algebra with impact factors
• Computer Science Conference Rankings