Logistic Regression programming assignment exercise 1

Exactly. Where is train_set_x_orig defined? Did you actually run that cell? Just having the code sitting there does nothing: you have to execute it and you need to do that again every time you open the notebook or do “Kernel → Restart …”.

BTW this was all explained in the video “A Quick Introduction to the Jupyter Notebooks” and the reading item “Programming FAQ” in Week 2 right before the assignments. If this is your first time using Jupyter Notebooks, it’s really worth going through those carefully. We’ll be spending a lot of time using the notebooks for all the assignments here, so you need to get familiar with how they work.