Array Indice Error For Loop

Following code is coming up with error "Array indices must be positive integers or logical values."

Does someone know what is causing this. Trying to store each value into an array

z =@(x) tan(x);
h = 0.5
for x=1:0.5:10
  Output (x) = (z(x+h)-z(x-h))/(2*h);
end
Array = [Output]

[Stephen23]

Note that your code can be trivially vectorized (a loop is a waste of time):

z = @tan;
h = 0.5;
x = 1:0.5:10;
y = (z(x+h)-z(x-h))./(2*h);

Learn how to write neat and efficient MATLAB code:

https://www.mathworks.com/help/matlab/matlab_prog/vectorization.html

Answer 1

[madhan ravi]

z =@(x) tan(x);
h = 0.5
x=1:0.5:10
Output = zeros(1,19) %preallocation for speed and efficiency
for i = 1:numel(x)
  Output (i) = (z(x(i)+h)-z(x(i)-h))/(2*h);
end
Array = Output

[madhan ravi]

you can access x(1.5)->(second iteration) because indexing should be real integers

[Stephen23]

@madhan ravi: where is the array preallocation? What do those square brackets do? (Hint: nothing)

[madhan ravi]

Thank you Stephen (edited now)