Cant get the Subs to input into my partial Derivatve

This is my Code

 %
syms R1 R2 R3 R4 R5 R6 R7
f=R1+((R2+((R4*(R5+R6+R7))/(R4+R5+R6+R7)*R3))/((R3+R2+(R4*(R5+R6+R7))/(R4+R5+R6+R7))));
P=diff(f,R1);
subs(P,{R1,R2,R3,R4,R5,R6,R7},{220,150,270,100,330,47,390})

and to check it partial with respect to R1 shold be 220 I keep getting 1

Im trying to take the partial derivative of a long formula for Resistor Eq. and cant get the final value to display. Please help

Answer 1

[Walter Roberson]

Your expression has R1 plus an expression that does not involve R1. Differentiate with respect to R1 and the answer is going to be diff(R1,R1) + diff(something independent of R1,R1) which is going to be 1 + 0 = 1.