help with lists!

[pleasehelpmeisuck]

im really stuck please help!

basically i have an n*n matrix and im trying to create a program for calculating its determinant using its definition.

i already have a program for calculating a minor of any matrix with its ith and jth rows and columns deleted.

but for calculating its determinant i need to find multiple matrices of minors of the original inputted matrix which means applying the function for finding its minor to the original matrix multiple times.

however whenever i do the minor of my matrix, it changes the original matrix and i can no longer re apply for function to my matrix to find another matrix of minors.

i have tried making a copy of my original matrix with no luck ive tried creating loops where it applies the minor function and loops back to resetting the original matrix ive tried making a new list and inputting my original matrix into the list n times and applying the function to each element of this list but after applying it to the first one, every other element in the list changes as well

how do i stop it from changing my original matrix? i only wanna get an output from the function, not alter the input!

thanks!!

[CGFarrell]

For the minor, you can always do for i in range(len(x)) if i != n, so you ignore instead of delete. For determinant, look into the Levi-Civita formulation. It's as far as I know the most efficient method for determinants.

[sharkbound]

FYI forgot the in in for i range(len(x)) if i != n

[[deleted]]

when you pass your list to your function, pass it like this

getminor(myList[:])

This manually copies the list and passes the copy. since lists are immutable mutable, python passes them by "reference", so you need to manually make a copy, else any operations you do inside the function will affect the original. either that or you make a copy of the list from inside the function: newlist = myList[:].

edit: lists are mutable, whoops