Hp50 Real Matrix does not allow subst aij real by a'ij complex

[Gil]

Nice solution.

But before getting my complex number to be replaced in your suggested form,
I have a negative number c, of which I take the nth root.

And c n 1/x ^ gives a z of a form (a,b), not directly 'a+bi'.

I can't find (any more?) a very simple way (flag setting or command)
to transform my (a, b) into your 'a+bi'
or to get directly, from c n 1/x ^, the requested form 'a+bi'.