Negate an equation:

[DrD]

Well, I tried many similar variants, but not precisely that ... I was hoping you would set me on the right path! For one thing, I was using EXPR, not expr, and it doesn't work with the upper case version. I like your method much better than the long winded version I've shown.

There is one other thing, it turns out that the last function in the list is the only one needing change of signs. So, in general, I can use something like:

L0(SIZE(L0));

To reach the objective in any size list of string elements. However that approach doesn't work in the CAS world, frustrating something like this:

STRING(CAS("-expr(L0( SIZE(L0) ))"));

This WILL work, however:

N:=SIZE(L0);
STRING(CAS("-expr(L0(N))"));

Would you have any thoughts on how to adapt your excellent method to any size list, in general?