MATLAB: Solution using newton raphson method

newton raphsonmethod

this is my code i am unable to substitue x1,x2,x3,x4 values in the matrix.Please help in solve this.
syms  x1 x2 x3 x4
g1=cos(x1)+cos(x2)+cos(x3)+cos(x4)-0.9424;
g2=cos(5*x1)+cos(5*x2)+cos(5*x3)+cos(5*x4);
g3=cos(7*x1)+cos(7*x2)+cos(7*x3)+cos(7*x4);
g4=cos(11*x1)+cos(11*x2)+cos(11*x3)+cos(11*x4);
g=[g1;g2;g3;g4];
x=[x1;x2;x3;x4];
j=jacobian(g,x)
j_inv=inv(j)
p=j_inv*-g
x1=input('enter initial values of x1')
x2=input('enter initial values of x2')
x3=input('enter initial values of x3')
x4=input('enter initial values of x4')
disp(x)
disp(p)
subs(p)

Best Answer

MATLAB does not automatically know which values to substitute. You need to specify this in the call to subs() explicitly. Try the following code
syms  x1 x2 x3 x4
g1=cos(x1)+cos(x2)+cos(x3)+cos(x4)-0.9424;
g2=cos(5*x1)+cos(5*x2)+cos(5*x3)+cos(5*x4);
g3=cos(7*x1)+cos(7*x2)+cos(7*x3)+cos(7*x4);
g4=cos(11*x1)+cos(11*x2)+cos(11*x3)+cos(11*x4);
g=[g1;g2;g3;g4];
x=[x1;x2;x3;x4];
j=jacobian(g,x);
j_inv=inv(j);
p=j_inv*-g;
X1=input('enter initial values of x1');
X2=input('enter initial values of x2');
X3=input('enter initial values of x3');
X4=input('enter initial values of x4');
disp(x)
disp(p)
subs(p, [x1 x2 x3 x4], [X1 X2 X3 X4])
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