Thank you all for replys and comments. I did get assign to work. there was a duplicate entry ie 2 rows the same which caused the problem. To clarify a some of the ponts raised. The rows are dependant on the previous rows. I choose a matrix because in a previous post Iwas told lists can be inefficant. Also athe matrix is visually easy to read I find. What I posed was just a short made up example. Thr algsubs on the equations is to shorten them as the can go on for screenful after screenfull. At the end of the assembling the equations I end uo with a 4x4 matrix whose determinant multiplies out to a 20th order polynomial. It is at this point I am using the assign to the valuse saved in the store matrix. I shall experiment with the

"#If you prefer assignment then you can use the two elementwise operations assign~ and  =~  : assign~(store[..,1]=~store[..,2]): a1,CX3,S1; "

At present I am using a for i to 100 do loop.