Changing a matrix from right-handed to left-handed coordinate system

Question

I would like to change a 4x4 matrix from a right handed system where:
x is left and right, y is front and back and z is up and down

to a left-handed system where

Answer 1

It depends if you transform your points by multiplying the matrix from the left or from the right.

If you multiply from the left (e.g: Ax = x', where A is a matrix and x' the transformed point), you just need to swap the second and third column. If you multiply from the right (e.g: xA = x'), you need to swap the second and third row.

If your points are column vectors then you're in the first scenario.