Can someone give an example of a for loop for this problem?: Find the sum of 30 numbers that increments by 3. The starting number is 4. Thanks!

Just a simple for loop please. Nothing too complicated. Thank you again.

[Steven Lord]

In general if you post a question like this that sounds like a homework assignment, even if it isn't a homework assignment, I recommend posting what you've tried and asking for help improving and/or fixing it. The problem might be as simple as a typo in your code, and seeing that code may allow someone to respond within seconds with the easy fix.

From your question itself, I'm guessing you're fairly new to MATLAB. If that's right, consider going through the free MATLAB Onramp course in the Tutorial section on the Support page if you haven't already. [Click Support in the bar at the top of this page.] It will teach you some of the basics of MATLAB and perhaps fill in any gaps in what you've learned so far.

[TSmith]

Ok. Thank you. Yes, I'm new to Matlab and just completed an intro course to it. I've understood everything so far except for and while loops. Thanks for your advice.

Answer 1

[Sean de Wolski]

x = sum(4:3:(4+3*(30-1)))

[TSmith]

Is this a for loop?

[madhan ravi]

@Stephen Cobeldick why do you keep voting up against me ? is it because I didn't respond to your comment?

[Guillaume]

"This is no longer homework. This is to study for my exam. I have tried looking up stuff, and that is why I am coming here for help."

"Is this a for loop?"

I would strongly suggest that you spend a lot more time studying for that exam if the answer to your "Is this a for loop?" question is not obvious. You have some serious catching up to do, which will not be solved by asking questions on Answers.

[Stephen23]

"why do you keep voting up against me ?"

I didn't. I voted for this because it demonstrates the simplicity of MATLAB, and I like to vote when an answer demonstrates a better use of MATLAB than what an assignment requires (loops seem to be a common favorite of some professors). Any answers that contain neat and efficient MATLAB code, or clear explanations of algorithms, etc, are possible candidates for my votes.

"is it because I didn't respond to your comment?"

Which comment?

[Sean de Wolski]

Is this a for loop?

No, but you could easily add a loop to it:

for ii = 1
    x = sum(4:3:(4+3*(30-1)))
end

[TSmith]

I meant, is this FOR a for loop. I didn't ask my question clearly. Sorry.

[John D'Errico]

@Madhan - don't worry about upvotes anyway. Reputation is not important, and there is no race to the top. Your responses are appreciated, improving the site with your presence, regardless of an upvote or not..

[madhan ravi]

@John D‘Errico thank you very much , really you are a gem :-)

Answer 2

[madhan ravi]

Read about sum() and cumsum() loops are superfluous in this case

[TSmith]

A = 1:10;
S = sum(A)

for 1:5
    sum(?)
end

Ok I found how to use sum, but how do I implement it within a for loop? I'd like to find the sum of 10 numbers with increments of 3 with the starting number being anywhere from 1 to 10.

[madhan ravi]

It's just like your previous question:

A=1:10;
total=zeros(1,numel(A)); % preallocate
for i=2:numel(A)
    total(i)=total(i-1)+3;
end
total

[Guillaume]

The efficient matlab way, which does not involve loops:

numbers = (1:10)' + [0 3 6]

and their sum

numbersum = sum(numbers, 2)

For pretty display

table(numbers, numbersum)

[madhan ravi]

Thank you very much Guillaume :) but the OP requires to use loops I suppose.

[Guillaume]

Indeed Madhan, but the OP is probably required to solve their homework themselves as well, not to subcontract it Answers.

[madhan ravi]

True..

[TSmith]

This is no longer homework. This is to study for my exam. I have tried looking up stuff, and that is why I am coming here for help.

[madhan ravi]

Yes I just saw your comment in your previous question @TSmith , Best of luck!

[TSmith]

Thank you!