Variable sized vectors and matricies where the components can be edited by the user

I am trying to make a comprehensive UNIFAC model program (it is an activity coefficient model used in chemical engineering). Currently I have it running and it works correctly, except for the user to be able to use this program for any size mixture system, they must edit the component matrices manually. For instance, if there are two species in the mixture, the user must edit the first vector to have two components and input the corresponding values, and they must edit the second matrix to have two rows and then they must input the corresponding values. What I want my program to be able to do is have the user input the number of components and this variable will produce both the vector and the matrix of the correct corresponding sizes. After these are created, then the user needs to be able to edit the values of the matrix and input the data that they need to run. I know how to make both vectors and matrices of variable sizes but what I need help with is making these resultant vectors and matricies able to be edited by the user to where they can input the data they need to run in the system.