Not sure what commands to use for eg. 0<x<a, when certain values are given

I'm trying to make a script that when values for Q, a and L are plugged in the following are computed (a random x variable in between the following):

   W          for 0 < x < a
Qw{
   0          for a < x < L

and

   -W(a-x)    for 0 ≤ x ≤ a
Mw{
   0          for a < x ≤ L

I'm not even sure where I would start to be able to do this, so any help would be appreciated. Even just some tips. Thanks for any advice guys!

[Image Analyst]

Where does Q come in to play?

[dave357]

sorry I made a mistake, by Q i meant W was going to be plugged in

[Image Analyst]

OK, so doesn't my code below do the trick?

Answer 1

[Kelly Kearney]

You might want to start by reading up on logical indexing (search the documentation). Your first example:

 Qw = zeros(size(x));
 Qw(x > 0 & x < a) = W;

Answer 2

[Image Analyst]

Try something like this:

L = 20
a = 3
W = randi(9, 1, L)
% Define x to have the same number of samples between 0 and L as W does.
x = linspace(0, L, length(W));
% Get two ranges
range1 = x<a
range2 = x > a
% Make arrays
Qw = zeros(1, length(W));
Qw(range1) = W(range1)
Mw = zeros(1, length(W));
Mw(range1) = -fliplr(W(range1))