Removing Multiples of a number from a Matrix

Hello all, I am very new to matlab as I am learning it for a lab i joined in school. Currently my job is only to learn matlab, functions, basics etc....

I was wondering if someone can tell me how to Remove multiples of a number from a given matrix.

For example:

Suppose i have a matrix that is

n = 1:1:20

I want to remove all the multiples of 2 from this matrix but NOT 2 such that when i displayed this "new" matrix without multiples of 2, matrix "m", it would return:

    disp(m)
    m = 1 2 3 5 7 9 11 13 15 17 19

would someone show me how i can do this? and also if there is a better approach to what i am doing? I want to avoid using plugins or anything, this is completely a learning experience and not something I will need to do in such large volumes that i would need a specific built in function / toolbox / plugin to do for me.

Thank you all.

Answer 1

[Sean de Wolski]

m = n; 
m(~mod(m,2)&m~=2) = []

remove parts that are divisible by two (~mod(m,2)) and not two, m~=2

[Mape]

Just tested this and it works!! awesome, thank you!

Sorry for being a noob but would you mind explaining what you just did here? =)

[Oleg Komarov]

m = m(logical(mod(m,2)) & m == 2); % (troll)

[Sean de Wolski]

exactly what I said:

I created a logical index of all values divisible by two:

~mod(m,2)

I then found all value of m not equal to two:

m~=2

I then used an AND to require that it be divisible be two AND not equal to two.

The value that were both I deleted by setting them to the empty set

= []

[Sean de Wolski]

Oleg, you and your glass half full optimism!! Wednesdays are clearly meant to be glass half empty...

[Mape]

Ah thank you, I just ran "help" right before i read this. Thanks again, when i meant new to matlab i also meant coding / programming in general, i have 0 prior knowledge.

Thank you both for posting.

[Sean de Wolski]

Welcome to MATLAB, programming and MATLAB answers!

A good idea to learn is to break every statement you see into its smallest components (as I did above), figure out what each one does and how they add up.

[Mape]

Thank you again, by the way would you have any recommendation in terms of books for complete beginners? I have never had a course on programming or anything. Currently I am using Essentials of Matlab by Hahn but a rather old edition i found in the lab. I use R2011a but i think this book is for an older version.

[Oleg Komarov]

BTW my troll answer has an error, it's | and not &

[Chase McDermott]

I am also new to Matlab, why do you have to put the "~" before the mod function?

Answer 2

[Jan]

The best method to learn Matlab is to use it. So how would you solve this?

One idea: Start from "n = 1:1:20" and look what happens, if the step width is set to 2: "1:2:20".

[Mape]

Thank you for your comment. While I know how to solve problems I see in a book on paper, its a different story on matlab. So therefore I create problems myself and see How i could solve them using matlab.

I'm also completely new to programming and Matlab is the first programming software/language I have ever used (just started a week ago). I also dont have a good book so I am trying to google and use the help functions as I try my best to learn Matlab.

[Sean de Wolski]

'lookfor'

will be your friend along with help.

[Jan]

And of course the "Getting started" chapters of the documentation.