norm calculation using for loop

hello , can anybody tell me how to calculate l2 norm of x=[2 3 -5 3 1] using for loop and without loop, and which one is efficient and fast?

Answer 1

[Adam]

n = norm( x );

does it without a loop. There is no reason to do it with a loop. Even if you don't use norm you would still vectorise is as:

n = sqrt( sum( x.^2 ) );

If you really want a loop the derivation is not difficult though. The vectorised version should certainly be faster, but you can test this yourself.

[g.p]

thanks adam , but i have to perform it element-wise using for loop ,and without for loop and need to justify which is fast.

[Adam]

If you have to perform it with a loop then I assume it is homework which you should be able to work out yourself from the 2nd version I gave above.

Converting this into a loop just uses the basics of Matlab:

n = sqrt( sum( x.^2 ) );

[Aash]

did u calculate it using for loops? how?

[KL]

As Adam has mentioned in his answer, loop is not necessary but if it's a homework and you must use a loop, then read the documentation to know how it works and then use the for loop iterator to index through the vector.

https://www.mathworks.com/help/matlab/matlab_prog/loop-control-statements.html