Difference between a<t<b and t>a && t<b
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Hi I am trying to verify existence of even and odd harmonics in e^(-t) periodic with period pi. For that I try to verify f(t)=f(t+pi). and for f(t+pi) i try to add shift using if-else condition according to this link answer should have even harmonics, http://www.intmath.com/fourier-series/5-harmonic-analysis.php I am trying to solve Example 2(b) in Matlab.
Now if i use the condition 0<=t(i)<pi it shows me even harmonic but if i use 0>=t(i) && t(i)<pi it gives neither even nor odd.
So, my question is why isn't Matlab showing same result for both formats. and which format is correct.
采纳的回答
The first form is not going to give you the result you expect, it is equivalent to:
(0 <= t(i)) < pi
Thus, it will compare t(i) to 0, and the result is either 1 (true) or 0 (false). It then compares that 0 or 1 to pi, which is always smaller. Hence the result will always be true.
The second form is the correct one. You can't link comparisons. You have to perform them one at a time and link the results with logical operators.
5 个评论
Ahmet Cecen
2015-4-28
You are kidding me, how have I not noticed this years an years of writing conditionals in MATLAB... I wonder if I just got lucky or there is a bug somewhere in some of my old codes...
Guillaume
2015-4-28
I'm not kidding. I don't think there are many languages where chaining comparisons would work since the result of the first comparison is normally a boolean.
John D'Errico
2015-4-28
If you have been doing this for years, then there are definitely bugs hidden in your code.
Ahmet Cecen
2015-4-28
Thankfully I found only one in a rotation code for visualization. Apparently I like to separate out the conditionals by default. Still many thanks for pointing this out, could have been a disaster. Would give more bumps if I could!
Maheen
2015-5-1
更多回答（1 个）
Ahmet Cecen
2015-4-28
might be because you are supposed to write:
*t(i)>=0 && t(i)<pi*
NOT:
*0>=t(i) && t(i)<pi*
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