MATLAB: What is wrong with the following while loop

fibonacci numbermatlab function

function [F] = get_fib(k)
get_fib(1) = 1;
get_fib(2) = 1;
get_fib(3) = 2;
i = 3;
k >= 0;
while i<=k;
    [F] = get_fib(i-1) + get_fib(i-2);
    i = i + 1;
end

Best Answer

As soon as you did

get_fib(1) = 1;

then you redefined "get_fib" inside the function so that it no longer refers to the function and instead refers to an array of double.

If you are intending to work recursively then you should not have the loop. If you are intending to not work recursively then you need the output, F, to be assigned to get_fib(k)

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MATLAB: Fibonacci Using While Loop

You don't assign your iterative result to the fibonacci array. E.g.:

    fibonacci(i) = fibonacci(i-1) + fibonacci(i-2);

HOWEVER, this formulation is increasing the size of the fibonacci variable in a loop, which can have severe timing consequences unless the parser saves you. I would advise that you reformulate your code to pre-allocate this array, or since you don't need to save the array work with only three values at a time ((i-2)'th, (i-1)'th, and i'th) using only three variables (e.g., fibonacci2, fibonacci1, fibonacci0).

MATLAB: Problem output of two loops

In the loop, use a 2D array for f which depends on i and k:

for k = 1 : 6
  for i = 1 : length(X)
    f(k, i) = the function that takes k and X(i) as input arguments
  end % of loop over i
end % of loop over k

Or, just in case you got your k and i mixed up, you can do it over only k

for k = 1 : 6
  f(k) = the function that takes k and X(k) as input arguments
end % of loop over k

Use whichever way you were thinking of.

Best Answer

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MATLAB: Fibonacci Using While Loop

MATLAB: Problem output of two loops

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