find a values in matrix

2 vues (au cours des 30 derniers jours)
Tomas
Tomas le 23 Nov 2013
Modifié(e) : dpb le 24 Nov 2013
I have matrix H[ 0 2.3926
2.3926 0]
I want to find value in matrix H, 2.3926 and store it in a variable A

Réponse acceptée

Azzi Abdelmalek
Azzi Abdelmalek le 23 Nov 2013
Maybe you are looking for the location
H=[ 0 2.3926
2.3926 0]
[ii,jj]=find(H==2.3926)

Plus de réponses (1)

dpb
dpb le 23 Nov 2013
Modifié(e) : dpb le 23 Nov 2013
val=2.3926;
A=H(abs(H-val)<1.e-5);
NB the "fuzzy" comparison to avoid FP precision problems
  2 commentaires
Tomas
Tomas le 23 Nov 2013
Modifié(e) : Tomas le 23 Nov 2013
little easier ?
will it work on different numbers in the matrix?
dpb
dpb le 23 Nov 2013
Modifié(e) : dpb le 24 Nov 2013
Not sure what the question is, precisely. Of course the comparison can be any value or range of values. There are times when owing to FP rounding find(x==val) won't return what is naively expected.
You can always write
A=H(H==2.3926);
and for some cases you'll find joy, in others "not so much"
Look up "logical addressing" in the documentation for more detail of how this works.

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