Array Indice Error For Loop

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HoboHarry
HoboHarry 2018-10-25
编辑： Stephen23 2018-10-25
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]
  1 个评论
Stephen23
Stephen23 2018-10-25
编辑：Stephen23 2018-10-25
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

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madhan ravi
madhan ravi 2018-10-25
编辑：madhan ravi 2018-10-25
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
  3 个评论
显示 1更早的评论
Stephen23
Stephen23 2018-10-25
@madhan ravi: where is the array preallocation? What do those square brackets do? (Hint: nothing)
madhan ravi
madhan ravi 2018-10-25
Thank you Stephen (edited now)

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