As can be seen in the first attachment, the prior mentioned vectorized error function was producing erroneous results.
?? Do you mean because the first value differs from the others? This is because your k-loop runs from 1 to last(E) and not from 0 to last(E) as it should. Unless changed Mathcad defaults to begin indexing with 0, not with 1.
The solve block finds no solution, as the way you did it can not work. In the solve block function A.c and E are scalars, but a and b are still vectors.
For individual error checking you have to change the solve block to work with scalars only. See attached