how to substitute sym variables in jacobian matrix with numeric values?

syms x y z

u = -Iscr + Iph - (x * ((exp((Iscr*y)/(n*Vth)))-1)) ...

- ((Iscr*y)/z);

v = Iph - (x * ((exp((Vocr)/(n*Vth)))-1)) - ((Vocr)/z);

w = -Im + Iph - (x * ((exp((Vm + Im*y)/(n*Vth)))-1))...

- ((Vm + (Im*y))/z);

a= jacobian([u;v;w],[x,y,z])

j=subs(a,[x,y,z],[xo,yo,zo]) %% This doesn't work, please explain why and also the alternative to this.

Answer 1

[Devineni Aslesha]

The ‘subs’ function works as expected. Please find the code shown below.

Iscr = 1;
Iph = 2;
Vth = 5;
n = 4;
Vocr = 3;
Im = 2;
Vm = 5;
syms x y z
u = -Iscr + Iph - (x * ((exp((Iscr*y)/(n*Vth)))-1)) ...
    - ((Iscr*y)/z);
v = Iph - (x * ((exp((Vocr)/(n*Vth)))-1)) - ((Vocr)/z);
w = -Im + Iph - (x * ((exp((Vm + Im*y)/(n*Vth)))-1))...
    - ((Vm + (Im*y))/z);
a = jacobian([u;v;w],[x,y,z]);
j = subs(a,[x,y,z],[1,2,3]);