MATLAB: How to put value in symbolic variable in differential equation (Newton Raphson Method)

newton raphsonsym

hi
i need help in the following code. i require "df" value in numeric form but here i get the complete expressions due to syms alpha1 alpha2 alpha3. Kindly help me and guide me how i get results of "df" and "inv(df)" in numeric format. kindly help me please 🙂
with best regards Mudasir
alpha1=0.2;            
alpha2=0.4;
alpha3=0.6;
v1desired=10;
T=[v1desired 0 0]';
f1=[ cos(alpha1)+cos(alpha2)+cos(alpha3)         
     cos(5*alpha1)+cos(5*alpha2)+cos(5*alpha3)   
     cos(7*alpha1)+cos(7*alpha2)+cos(7*alpha3)];
   syms alpha1 alpha2 alpha3
            f=[ cos(alpha1)+cos(alpha2)+cos(alpha3)         
              cos(5*alpha1)+cos(5*alpha2)+cos(5*alpha3)   
              cos(7*alpha1)+cos(7*alpha2)+cos(7*alpha3)];
df=jacobian(f,[alpha1;alpha2;alpha3])  
dalpha=(inv(df))*(T-f1);

Best Answer

v_alpha1=0.2;            
v_alpha2=0.4;
v_alpha3=0.6;
v1desired=10;
T=[v1desired 0 0]';
syms alpha1 alpha2 alpha3
f1 = [ cos(alpha1)+cos(alpha2)+cos(alpha3)         
     cos(5*alpha1)+cos(5*alpha2)+cos(5*alpha3)   
     cos(7*alpha1)+cos(7*alpha2)+cos(7*alpha3)];
f = [ cos(alpha1)+cos(alpha2)+cos(alpha3)         
     cos(5*alpha1)+cos(5*alpha2)+cos(5*alpha3)   
     cos(7*alpha1)+cos(7*alpha2)+cos(7*alpha3)];
df = jacobian(f,[alpha1;alpha2;alpha3])  
dalpha_sym = (inv(df))*(T-f1);
dalpha = double( subs(dalpha_sym, [alpha1, alpha2, alpha3], [v_alpha1, v_alpha2, v_alpha3]));
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