Thanks you very much,
Can you please let me know if I am right about how you corrected this for me? (i just want to understand totally)
when you wrote:
tfn(finalCoOEPcon, finalconcoronene) := find(t)
you actually defined the function "tfn" to calculate "t" and it just tells mathcad to change the two parameters to find "t". right?
and when you said:
t[i := tfn(finalCoOEPcon, finalconcoronene)
we put the value of tfn to t[i.