How to display a certain answer

I currently have the output

If I only want to display the value of w(i,j) for, let's say, when xi=0.5 and tj=0.3 (so the answer should be -0.2781152949), how do I do it?

I wanna do something like

fprintf( 'The value of w when x = %.1f and t = %.1f is %.10f \n',xi, tj, wij(i,j));


%this is my code by the way, for reference

%Step 0
l= 1;   
T= 0.5; 
alpha = 1;   
m=10; 
N=5;
syms f(x) g(x)
f(x)= 0.9*cos(2*pi*x);
g(x)= 0;
%STEP1
h=l/m;
k=T/N;
lambda=k*alpha/h;
%STEP2
wij = zeros(m,N);
for j=2:N %j=1:N
    wij(1,j)=0; %wij(0,j)
    wij(m,j)=0;
end
%STEP3
wij(1,1)=f(0); %wij(0,0)
wij(m,1)=f(l); %wij(m,0)
%STEP4
for i=2:m-1 %i=1:m-1
    wij(i,1)=f(i*h); %wij(i,0)
    wij(i,2)=(1-lambda^2)*(f(i*h))+((lambda^2)/2)*(f((i+1)*h)+(f((i-1)*h))+k*(g(i*h))); %wij(i,1)
end
%STEP5
for j=2:N-1 %j=1:N-1
    for i=2:m-1 %i=1:m-1
        wij(i,j+1)=2*(1-lambda^2)*wij(i,j)+lambda^2*(wij(i+1,j)+wij(i-1,j))-wij(i,j-1);
    end
end
%STEP6
disp('xi   tj      w(i,j)')
for j=1:N %j=0:N
    t=j*k;
    for i=1:m %i=0:m
        x=i*h;
    end
end

%i am planning to print here

Answer 1

[Walter Roberson]

[first_found, first_idx] = ismembertol(xi, list_of_xi);
[second_found, second_idx] = ismembertol(tj, list_of_tj);
if first_found && second_found
    fprintf( 'The value of w when x = %.1f and t = %.1f is %.10f \n',xi, tj, wij(first_idx,second_idx));
else
    fprintf('Nothing close enough to x = %.1f and t = %.1f exists in the matrix\n', xi, tj)
end