a = b<0
9 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
What is the meaning of this line?
...
a = b<0;
c = 3*a;
...
Is a IF condition?
0 commentaires
Réponse acceptée
Voss
le 22 Jan 2023
Modifié(e) : Voss
le 22 Jan 2023
a = b<0;
checks if b is less than 0 and stores the result in a.
If b is a scalar: if b is less than 0, then a will be true; otherwise a will be false.
If b is a non-scalar array: a will be a logical array the same size as b, with each element being true or false, depending on whether the corresponding element in b is less than 0 or not.
Examples:
b = 2;
a = b<0 % false
b = -2;
a = b<0 % true
b = 0;
a = b<0 % false
b = randn(3) % non-scalar array
a = b<0 % 3-by-3 logical array, true where b<0 and false elsewhere
Then the next line
c = 3*a;
multiplies a by 3 and stores it in c, so c will be an array the same size as a, with the value 3 where a is true and the value 0 where a is false.
Examples:
b = 2;
a = b<0; % false
c = 3*a
b = -2;
a = b<0; % true
c = 3*a
b = 0;
a = b<0; % false
c = 3*a
b = randn(3) % non-scalar array
a = b<0 % 3-by-3 logical array, true where b<0 and false elsewhere
c = 3*a
0 commentaires
Plus de réponses (1)
Torsten
le 22 Jan 2023
Modifié(e) : Torsten
le 22 Jan 2023
"a" is a logical variable.
It is set to "true" (=1) if b<0, else it is set to "false" (=0).
The next operation c = 3*a works as if "a" was a double variable.
Thus c = 3*1 = 3 if "a" was "true", else c = 3*0 = 0 if "a" was "false".
0 commentaires
Voir également
Catégories
En savoir plus sur Structures dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!