Why do I get this result??

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Carole
Carole on 7 Nov 2012
Hello
I have a problem with this code
k=2*A+3*B
if k<3.65
fr='inf'
elseif 3.65<k<=4.35
fr='moy'
elseif k>4.35
fr='sup'
end
why i get this result 'moy'?? it must be 'sup'
k =
6.4582
fr =
moy
Can you help me to correct this code.

Accepted Answer

Evan
Evan on 7 Nov 2012
Edited: Evan on 7 Nov 2012
The below line is the culprit:
elseif 3.65<k<=4.35
Specifying inequalities in matlab isn't done in the same notation as you might when writing them. If you need to find when a value is between an upper and lower bound, do something like this:
elseif 3.65 <= k && k <= 4.35
The way you have it, matlab evaluates the statement from left to right. So, if k = 6.4582, these will be the steps matlab performs:
1. (3.65 < k) <= 4.35
2. (1) <= 4.35
3. 1
Because the expression in parenthesis is true, it evaluates to "1." This leaves 1 <= 4.35, which will also return 1. But your value was 6.4582, meaning the code didn't do what you intended!
Instead, include each condition in your if statement, separating them with && symbols.

More Answers (2)

David Barry
David Barry on 7 Nov 2012
Try this
k=2*A+3*B
if k<3.65
fr='inf'
elseif k >= 3.65 && k<= 4.35
fr='moy'
elseif k>4.35
fr='sup'
end
  3 Comments
David Barry
David Barry on 7 Nov 2012
Also note that I have changed your code to cope when k = 3.65
Evan
Evan on 7 Nov 2012
Good catch. I didn't notice that. I've updated my post to account for that issue, but credit goes to you. :)

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Sean de Wolski
Sean de Wolski on 7 Nov 2012

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