I am trying to create a program in spark that will run a multiple regression for my master's dissertation. I am using the standard formula for the calculation of b with the matrices. When I do the process 'by hand' the results coming out of my program are the same, but when I compare my results with spss they differ. Can someone please tell me which formula is used by spss (method: enter) for the calculation of multiple regression? Do you know what might be wrong with what I'm trying to do and I'm not getting the same results?

Thanks in advance!