Preallocated array A using a for loop

Consider an iterative series 1, (-1)/2, 1/3, (-1)/4, 1/5,…(-1)^(k-1)/k. The first 5 terms for k=1:5 are written here. Create the first 100 and store them all in a preallocated array A using a for loop.

Please help with this question. Thanks in advance!

Answer 1

[madhan ravi]

https://in.mathworks.com/help/matlab/matlab_prog/preallocating-arrays.html - you will see how to store values in each iteration through preallocation.

[timetry2]

I did look through this already, however, I am still confused on how to exactly code it to do a for loop. Could you show me how the code itself would look like.

Thank you

[madhan ravi]

Just come up with the code , doesn’t matter if it’s right or wrong. We’ll correct the code once it’s constructed.

[timetry2]

Im unfamiliar with tic toc functions but here is the code I came up with:

tic
x = zeros (1,100);
for k = 1:5
x(k)=(-1)^(k-1)/k
end 
toc 

Please let me know what to fix and thanks for the help!

[madhan ravi]

Ignore tic toc , concentrate the length of k you are only calculating until 5 but the task asks you to do it till 100.

[timetry2]

So, would I just need to change k = 1:100 instead of k = 1:5?

So, the line of code would look like the following:

tic
x = zeros (1,100);
for k = 1:100
    x(k) = (-1)^(k-1)/k
end 
toc

[Image Analyst]

Correct.

[timetry2]

One last thing, what are the tic toc functions doing then? I've only learned about for and while loops. And, I was curious how this function works without incorporating either. Thank you so much for the help.

[madhan ravi]

https://in.mathworks.com/help/matlab/ref/toc.html?searchHighlight=tic%20toc&s_tid=doc_srchtitle