I can’t figure out where is a mistake here. Is it because I am unintentionally aliasing here (“theta_plus” is also set to theta_plus=np.copy(parameters_values)? Please advise.
Hi @Robert_Ascan ,
Looking at your attachment, it is very likely to do with a mismatch of parenthesis from previous line of code. So just check for that.
Exactly! That was going to be my theory as well. When you can’t find a syntax error, it usually means you are looking in the wrong place. 
Spot-on! Thanks a lot!