I need help due to unrecognized function or variable ' x ' error, please.

Answer 1

[Sulaymon Eshkabilov]

Here is how to call a function

x = linspace(-10,10);
f=randi(15, size(x));
ANSWER = dd(x,f)

ANSWER = 1×100

1.0e+03 * 0.0140 -0.0099 -0.0858 0.3436 -0.5003 -0.0743 1.7367 -3.9587 5.6320 -5.9887 5.1183 -3.6821 2.3249 -1.3547 0.7778 -0.4700 0.3062 -0.2078 0.1389 -0.0877 0.0513 -0.0275 0.0135 -0.0061 0.0025 -0.0010 0.0003 -0.0001 0.0000 -0.0000

function a = dd(x, f)
n = length(x);
a =f;
for jj=2:n
for ii=n:-1:jj
a(ii) = (a(ii)-a(ii-1))/(x(ii)-x(ii-jj+1));
end
end
end

[B]

The unrecognized function or variable ' x ' error still persists.

[Walter Roberson]

@B

The output shown above, the "ANSWER = " and so on, is output from executing the code here in MATLAB Answers. The code runs successfully, with no error about x

Answer 2

[Sulaymon Eshkabilov]

Put this code in one M-file or MLX editor window, and hit ctrl+enter

x = linspace(-10,10);
f=randi(15, size(x));
ANSWER = dd(x,f)
function a = dd(x, f)
n = length(x);
a =f;
for jj=2:n
for ii=n:-1:jj
a(ii) = (a(ii)-a(ii-1))/(x(ii)-x(ii-jj+1));
end
end
end