# Creating a function in MATLAB

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Saurabh Madankar on 11 Feb 2022
Commented: Walter Roberson on 11 Feb 2022
I need to create a function with input i and outputs j and k. So i varies from 1,2,3... and i,j and k are related as , where j =0,1,2,... and k=0,1,2,...,. So,
for input i=1, outputs should be j=0,k=0;
i=2 j=1,k=0;
i=3 j=1,k=1;
i=4 j=2,k=0;
i=5 j=2,k=1;
i=6 j=2,k=2;
i=7 j=2,k=3;
and so on. How do I create such a function?

Walter Roberson on 11 Feb 2022
for I = 1 : 10
[J, K] = decode(I);
fprintf('i = %d, j = %d, k = %d\n', I, J, K);
end
i = 1, j = 0, k = 0 i = 2, j = 1, k = 0 i = 3, j = 1, k = 1 i = 4, j = 2, k = 0 i = 5, j = 2, k = 1 i = 6, j = 2, k = 2 i = 7, j = 2, k = 3 i = 8, j = 3, k = 0 i = 9, j = 3, k = 1 i = 10, j = 3, k = 2
function [j, k] = decode(i)
L2 = nextpow2(i);
if 2.^L2 == i
j = L2;
k = 0;
else
j = L2 - 1;
k = i - 2.^j;
end
end
Saurabh Madankar on 11 Feb 2022
Edited: Saurabh Madankar on 11 Feb 2022
Thanks a lot, I didn't know about the built in function nextpow2. I went through the documentation and now have understood how this code works.
Walter Roberson on 11 Feb 2022
j = floor(log2(i)) ;
k = i - 2.^j;
... a vectorized version