This function cannot be used here

[ptc-3679927]

Hello all, 

Need help with the root function which i keep getting the error 'This function cannot be used here'.

(mathcad 15)

Thank you. 

[Werner_E · Accepted solution]

The function you feed into "root" returns a vector as a result but to make "root" work it has to be a scalar valued function.

Not sure if you get what you are looking for if you turn Py and Pc into functions of t AND i:

[ptc-3679927]

Thank you!