# Why is this generating a numerical array and not an array of cells?

3 vues (au cours des 30 derniers jours)
Nicholas Kavouris le 17 Mar 2022
Commenté : Image Analyst le 17 Mar 2022
Why does the following loop generate slope as the result of diff() function? Instead or a cell array with the desired text?
for i=1:length(Temp_F)
if diff(Temp_F(i))>0
slope(i)='Rising'
elseif diff(Temp_F(i))<0
slope(i)='Falling'
end
end
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Stephen23 le 17 Mar 2022
diff(Temp_F(i))
What do you expect the difference of one number to be?

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### Réponse acceptée

KSSV le 17 Mar 2022
REad about the function diff. It needs an array with atleast 1x2 dimensions. You are giving only one number as input. So diff gives you an empty matrix.
diff(1)
ans = []
diff(rand)
ans = []
diff(rand(1,2))
ans = 0.0347
diff(rand(2,1))
ans = 0.5240
So you have to modify your code like below:
diff_Temp_F = diff(Temp_F) ; % I assume Temp_F is a vector
N = length(Tmp_F) ;
slope = cell(N,1) ;
for i=1:length(Temp_F)-1
if diff_Temp_F(i) > 0
slope{i}='Rising'
elseif diff_Temp_F(i) < 0
slope{i}='Falling'
end
end
##### 1 commentaireAfficher -1 commentaires plus anciensMasquer -1 commentaires plus anciens
Image Analyst le 17 Mar 2022
I believe you could also use strings instead of character arrays and then use parentheses instead of braces
slope(i) = "Rising"; % Use double quotes instead of single quotes.

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