solution using newton raphson method?

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omkari sai krishna 2020-4-19

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https://ww2.mathworks.cn/matlabcentral/answers/519092-solution-using-newton-raphson-method

评论： omkari sai krishna 2020-5-3

采纳的回答： Ameer Hamza

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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)

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采纳的回答

Ameer Hamza 2020-4-19

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https://ww2.mathworks.cn/matlabcentral/answers/519092-solution-using-newton-raphson-method#answer_426975

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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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omkari sai krishna 2020-4-20

编辑：Ameer Hamza 2020-4-20

在 MATLAB Online 中打开

Sir i am working with your suggestion but i am not getting correct solution using this code i am not understanding what will be reason. Please help me to know the concept.

clc;clear all
syms  x1 x2 x3 x4 X1 X2 X3 X4
g1=cosd(x1)+cosd(x2)+cosd(x3)+cosd(x4)-0.9424;
g2=cosd(5*x1)+cosd(5*x2)+cosd(5*x3)+cosd(5*x4);
g3=cosd(7*x1)+cosd(7*x2)+cosd(7*x3)+cosd(7*x4);
g4=cosd(11*x1)+cosd(11*x2)+cosd(11*x3)+cosd(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');
X=[X1;X2;X3;X4];
while (1)
    k=double(subs(p, [x1 x2 x3 x4],[X1 X2 X3 X4]));
    if k(1,1)&&k(2,1)&&k(3,1)&&k(4,1)<0.000001
        disp(X1)
        disp(X2)
        disp(X3)
        disp(X4)
        disp(k)
        break
    else
        y1=X1+k(1,1);
        y2=X2+k(2,1);
        y3=X3+k(3,1);
        y4=X4+k(4,1);
        X1=y1;
        X2=y2;
        X3=y3;
        X4=y4;
        
    end
end