Why doesn't my code work correctly?

Hi

c0 must be numeric, but my symbolic functions can not work correctly?

Where is my mistake?

Thx

clear all

clc

syms x1 x2
F=x1^2+x2^2-4*x1-2*x1*x2;
gradx1=gradient(F,x1); 
gradx2=gradient(F,x2);
c=[gradx1; gradx2];

fun_x0=@(x1,x2) F;
fun_c1_x0=@(x1,x2) gradx1;
fun_c2_x0=@(x1,x2)  gradx2;
 
x0=[1,1];
c_x0_1=fun_c1_x0(x0(1),x0(2));
c_x0_2= fun_c2_x0(x0(1),x0(2));
c0=[c_x0_1; c_x0_2];
c0=c0';

 

Answer 1

[madhan ravi]

Because you mixed function handle in place of subs()/matlabFunction().

Try this:

syms x1 x2 
F=x1^2+x2^2-4*x1-2*x1*x2;
gradx1=gradient(F,x1); 
gradx2=gradient(F,x2);
c=[gradx1; gradx2];
fun_x0= F;
fun_c1_x0=gradx1
fun_c2_x0=gradx2 
x0=[1,1];
c_x0_1=subs(fun_c1_x0,{x1,x2},{x0(1),x0(2)});
c_x0_2=subs(fun_c2_x0,{x1,x2},{x0(1),x0(2)});
c0=[c_x0_1; c_x0_2];
c0=c0.'

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Thanks a lot

[madhan ravi]

Anytime :) , here is another simple way:

syms x1 x2 
F=x1^2+x2^2-4*x1-2*x1*x2;
gradx1=gradient(F,x1); 
gradx2=gradient(F,x2);
c=[gradx1; gradx2];
fun_x0= F;
fun_c1_x0(x1,x2)=gradx1;
fun_c2_x0(x1,x2)=gradx2;
x0=[1,1];
c_x0_1=fun_c1_x0(x0(1),x0(2));
c_x0_2= fun_c2_x0(x0(1),x0(2));
c0=[c_x0_1; c_x0_2];
c0=c0.'