# Transfer function : Complex network

For the attached circuit attached in LTspice spice, I am trying to find the transfer function interms of Rc1,Rc2,Rc3 and Rc4. For that I have switches which I configure to turn on/off and measure the various values of V(bip) and V(bin). Basically, The for the switches S1 and S2 (00 -- 11),I run a inner loop of Sx and Sy switches (00 -- 11) So, I get 16 combinations of V(bip) and V(bin) readings. Final Aim is to find out the sensitivity of Rc1--R4 w.r.t the Sx and Sy (R8-R11)node resistances, So the resistance at this node would change, the current values are just to solve the transfer function . But, the sheer number of equations are too much for me, solving using pen and paper. Is there simpler way to find the equations and if some approach could be suggested to derive it ? -----------------EDIT--------------------->>> Updated the with the equations as per the image, but while doing Find in Mathcad for Rc1-Rc4 the tool runs into runtime error

• @seeker In that case use AJN's suggestion. I deleted the answer because I calculated the resistance as seen from I1, not V(A,B) (also had a typo that resulted in 2/Ry, instead of 1/Rx+1/Ry). Commented Jun 30, 2021 at 20:27
• @aconcernedcitizen I have put the equations as per my edit in mathcad but the tool runs into runtime error while trying to calculate Rc1--Rc4. Commented Jul 1, 2021 at 6:17
• @AJN please refer my edit not sure why but the mathcad tool runs into runtime error while calculating the variables Rc1--Rc4. Commented Jul 1, 2021 at 6:18
• @AJN sure I could try. The matrix := Find(...), Find() calculates the different variables and the correspond values gets assigned to the matrix variable of size 9x1 in this case, If you want to access Va then use Matrix0,0-> Commented Jul 1, 2021 at 13:04
• – AJN
Commented Jul 1, 2021 at 13:19