How can I create an array with a for loop?

Hi I’m trying to create an array of values that are output from a function. The function goes from -20 to 50 but I can’t create an array that large so I’m confused on what to do. The attached picture is what I have so far and it’s not working.

    % code
 clear all;
close all;
A = zeros(1:70);
for m = 1:70;
    n = -50:20;
    X = power(0.8,n)
    A(m) = X
  end
    stem(n,arrayofA(n))

[Stephen23]

Do not use the accepted answer: a loop is NOT required:

n = -50:20;
A = power(0.8,n);

Answer 1

[Torsten]

A = zeros(1,71);
n = -50:20;
A = power(0.8,n)

[Jos (10584)]

This is preferred over the solution with a for-loop. However, there is no need to initialise A with zeros first, since you overwrite it at the third line.

Answer 2

[Birdman]

Try this:

A=zeros(1,70);n=-50:20;
for m=1:numel(n)
   A(m)=power(0.8,n(m));
end
stem(n,A)

[Paige Coffeen]

This one looks like it worked! Can you explain what is the m=1:numel(n) function doing? That seems to be the connecting factor I needed.

Thank you!!

[Birdman]

It is the condition for the loop to be operated. m starts at 1, incremented by 1 and the loop is over when m is equal to the number of elements in n vector, which is 71. At each step, the statement in for loop is executed and the result is stored in A array.

[Jos (10584)]

As Torsten showed, A = power(0.8,n) would do. No need for a for-loop

[Dennis M]

  y = zeros(1,12);
 for i = 1:12
    y(i+1) = y(i) + ((5 - (4/50)*y(i)));
 end
 y

y = 1×13

0 5.0000 9.6000 13.8320 17.7254 21.3074 24.6028 27.6346 30.4238 32.9899 35.3507 37.5227 39.5209

   x = zeros(1,10);
   for i = 10:-1:2
      x(i-1) = x(i) + ((5 + (4/50)*x(i)));
   end
   x

x = 1×10

62.4378 53.1831 44.6140 36.6796 29.3330 22.5306 16.2320 10.4000 5.0000 0

Good Day,

May I ask how can I insert the start and stop variable on above code? for example I want to start in 17 to 30 or 15 to 2 with decrementing step.

Thanks and Regards,

Dennis

[Walter Roberson]

You should ask your own question for that.