I want to find the value of k

syms x1 x2 x3

x=[x1;x2;x3];

f1=x(1)^3+12*x(2)+1;

f2=x(2)^9+5*x(1)-3;

f3=x(2)*x(3)^2+8;

k=[diff(f1,x(1)),diff(f1,x(2)),diff(f1,x(3));diff(f2,x(1)),diff(f2,x(2)),diff(f2,x(3));diff(f3,x(1)),diff(f3,x(2)),diff(f3,x(3))];

x=[2;5;9];

With these values of x

I want to find out the value of k, how do I do that ?

Answer 1

[John D'Errico]

syms x1 x2 x3
x=[x1;x2;x3];
f1=x(1)^3+12*x(2)+1;
f2=x(2)^9+5*x(1)-3;
f3=x(2)*x(3)^2+8;

Here is the matrix k.

k=[diff(f1,x(1)),diff(f1,x(2)),diff(f1,x(3));diff(f2,x(1)),diff(f2,x(2)),diff(f2,x(3));diff(f3,x(1)),diff(f3,x(2)),diff(f3,x(3))]

k = 

So, a function of x1, x2, and x3.

Why did you define x as x=[x1;x2;x3];, when you never used it again?

If you wish to substitute for x1, x2, x3, you could do this:

subs(k,[x1,x2,x3],[2 5 9])

ans = 

[SANDIPKUMAR ROYADHIKARI]

Ok, thanx sir