Does tilda in a function output give any speed up?

2 vues (au cours des 30 derniers jours)
Anton
Anton le 12 Mar 2016
Réponse apportée : Kuba le 25 Juil 2016
If, say, I use
[a,b,~]=svd(d);
instead of
[a,b,c]=svd(d);
should I generally expect any speed up and/or memory saving? Or it depends on the function I use and should be tested each time?

Réponses (3)

Star Strider
Star Strider le 12 Mar 2016
Time it and find out!
I doubt it, though. The value is still calculated, but no space is made for it in the calling function workspace.

Jan
Jan le 12 Mar 2016
From inside the function there is no way to check, if the 3rd agrument is caught in the caller or not. Therefor the runtime for the function must be the same. But the calling function can free the memory for the argument immediately. For huge arrays this can be an advantage under certain circumstances, but not in general.

Kuba
Kuba le 25 Juil 2016
And what about using tilda in input arguments, say:
[a,b,c]=svd(~, e);
Instead of:
[a,b,c]=svd(d, e);
Is there any difference in performance?

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