checking input an integer greater than 0?
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how can I check if my input is a integer greater than 0?
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John D'Errico
le 16 Nov 2020
Modifié(e) : John D'Errico
le 16 Nov 2020
If you want to check for an integer that exceeds zero, first use the && and || operators.
So assuming you want to throw an error if it fails, then I might do...
if (x <= 0) || (rem(x,1) ~= 0)
error('Oh nO, Mr. Bill! x was not a positive integer.')
end
You use the || operator here, because MATLAB is more efficient with them in an if statement. They short circuit the test, so if the first part of the test is true, then there is no need to even execute the second clause in the test. The && operator works the same way.
I might even have added a test that x be a scalar variable.
If your question is you want to do something specifically if x is a positve integer, then another ay to write it would be:
if (numel(x) == 1) && (x > 0) && (fix(x,1) == 0)
disp('Happy days are here again...')
else
error('Oh nO, Mr. Bill! x was not a scalar positive integer.')
end
As you can see, I even added a test that x be scalar. There are of course alternative ways to test for an element being an integer. (fix(x)==x) is another, or (round(x) == x). Note that all such tests, when applied to a scalar are all extremely fast. Actually, the slowest of them is the rem test I used above.
You should also see that when I changed the if statement, I now had to use &&, which is the short-circuited version that applies.
2 commentaires
James Tursa
le 16 Nov 2020
Your first suggestion covers the x==inf case, but the second formulation doesn't.
John D'Errico
le 17 Nov 2020
Good point. Best of course would be to explicitly test for inf or NaN input.
Ameer Hamza
le 16 Nov 2020
Modifié(e) : Ameer Hamza
le 16 Nov 2020
You can use this condition
tf = (x>0) & (round(x)==x)
Example
>> x = 5;
>> tf = (x>0) & (round(x)==x)
tf =
logical
1
>> x = 4.5;
>> tf = (x>0) & (round(x)==x)
tf =
logical
0
3 commentaires
Matt J
le 16 Nov 2020
Modifié(e) : Matt J
le 16 Nov 2020
validateattributes(yourInput,"numeric",{"integer","nonnegative"})
1 commentaire
John D'Errico
le 16 Nov 2020
"greater than 0"
validateattributes(yourInput,"numeric",{"integer","positive"})
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