MATLAB: Error : Too many input arguments using sym.subs. How to get rid of this

input argumentssymbolic

There are 2 symbolic substituions that I'd like to make in my code. All other variables are pre-defined.
syms s t
D = (E/(1-NU*NU))*[1, NU, 0 ; NU, 1, 0 ; 0, 0, (1-NU)/2];
d = (y1*(s-1)+y2*(-1-s)+y3*(1+s)+y4*(1-s))/4;
c = (y1*(t-1)+y2*(1-t)+y3*(1+t)+y4*(-1-t))/4;
a = (x1*(t-1)+x2*(1-t)+x3*(1+t)+x4*(-1-t))/4;
b = (x1*(s-1)+x2*(-1-s)+x3*(1+s)+x4*(1-s))/4;
B1 = [d*(t-1)/4-c*(s-1)/4 0 ; 0 a*(s-1)/4-b*(t-1)/4 ; a*(s-1)/4-b*(t-1)/4 d*(t-1)/4-c*(s-1)/4];
B2 = [d*(1-t)/4-c*(-1-s)/4 0 ; 0 a*(-1-s)/4-b*(1-t)/4; a*(-1-s)/4-b*(1-t)/4 d*(1-t)/4-c*(-1-s)/4];
B3 = [d*(t+1)/4-c*(s+1)/4 0 ; 0 a*(s+1)/4-b*(t+1)/4 ; a*(s+1)/4-b*(t+1)/4 d*(t+1)/4-c*(s+1)/4];
B4 = [d*(-1-t)/4-c*(1-s)/4 0 ; 0 a*(1-s)/4-b*(-1-t)/4 ; a*(1-s)/4-b*(-1-t)/4 d*(-1-t)/4-c*(1-s)/4];
Bfirst = [B1 B2 B3 B4];
Jfirst = [0 1-t t-s s-1 ; t-1 0 s+1 -s-t ;  s-t -s-1 0 t+1 ; 1-s s+t -t-1 0];
DetJ = [x1 x2 x3 x4]*Jfirst*[y1 ; y2 ; y3 ; y4]/8;
B = Bfirst/DetJ;
sigma = D*B*q;
w = subs(sigma, s,t, 0,0);
This last line produces an error using sym.subs: too many input arguments. Why is this happening? How can I fix this?

Best Answer

w = subs(sigma, {s,t}, {0,0});
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