Numerical derivative central difference

Hello, i try to write a code about central difference. But something is wrong. My code is below. What is wrong?

function derivativecentral(numericalvalue, step, n)
    centraltable=[0 -1 0 1 0;0 1 -2 1 0;-1 2 0 -2 1;1 -4 6 -4 1];
    x=numericalvalue-2*step: step:numericalvalue+2*step;
    m=2;

    if (n/2)==floor(n/2); m=1;  coeff = centraltable(n,:);
       der=sum(coeff.*fonk(x)) / (m*step^n);
       display(der);
    end
end


function [f] = fonk(x) f=x*exp(x); end

At the end of code, i am writing derivativecentral(0,0.1,1)

But there is nothing.

Answer 1

[Ameer Hamza]

The code displays nothing because the condition did not become true. Try the following code with a different input

derivativecentral(0,0.1,4)

function derivativecentral(numericalvalue, step, n)
    centraltable=[0 -1 0 1 0;0 1 -2 1 0;-1 2 0 -2 1;1 -4 6 -4 1];
    x=numericalvalue-2*step: step:numericalvalue+2*step;
    m=2;
    if (n/2)==floor(n/2); m=1;  coeff = centraltable(n,:);
       der=sum(coeff.*fonk(x)) / (m*step^n);
       display(der);
    end
end

function [f] = fonk(x) 
f=x.*exp(x); % <---- this is syntax for element-wise multiplication
end