question on months&days in 2012

I'm unable to complete this assigment; solutions welcome! I've only started using MATLAB last week (so yes, I'm aware this is basic). https://gyazo.com/c707328e01a308366fae5147aef147bc

[jonas]

Well, what have you tried?

[Danny Browne]

Sorry for the poorly structured question! My attempt: https://gyazo.com/d8fc6a2e340b15db05f06422fbf91a42 - unsure of how to answer the final two parts.

[jonas]

Good start. Just know that you can use several conditions in one go. For example:

if m<1 | m>12

where | means OR. I think multiple conditions are needed to solve the last part. One approach would be to check if the day is equal to (==) 30 and (&) month equal to (==) one of the months with 30 days in it. You can use "ismember" to check if one number is present in a set of numbers.

[Danny Browne]

https://gyazo.com/5091c0e2307f768e0001307c17cb60d3 Think I got it; thanks for the tips!

[jonas]

One of your conditions basically reads like this:

if A==1 | 2 | 3

That is not how to write a condition.

A loop is executed when the condition returns true. The condition above will always return true, for any month or day. Basically you can test the condition like this:

A=1;
logical(A==0 | 2)

ans =

logical

   1

What?! A is not equal 0 nor 2, why does it return true (1)? As the condition is written, true will be returned if any one of the two separate conditions are satisfied, and the logical of anything other than zero (such as 2) returns true.

logical(-1)

ans =

logical

   1

The correct way would be

if A==1 | A==2 | A==3

or

if ismember(A,[1 2 3])

Answer 1

[jonas]

Now that you've basically solved it, here is my (hopefully correct) solution. Note that for scalars you can write && instead of &. It is a bit faster, because not all conditions are necessarily checked.

d = 31;
m = 4;

% Check day
if d>=0 && d<=31
    disp('OK')
else 
    disp('not OK')
end

% Check month
if m>=1 && m<=12
    disp('OK')
else 
    disp('not OK')
end

% Check day & month
if d==31 && ~ismember(m,[1 3 5 7 8 10 12])
    disp('not OK')
elseif (d==30 || d==29) && m==2
    disp('not OK')
else
    disp('OK')
end