Should I be using a 'switch' in this case? I am new to matlab and have never used 'switch' before. Can someone please help?
Problem in if-else if-else structure
3 views (last 30 days)
Show older comments
Hi, I have written the following program. But it does not output the result I get from manual calculations. Perhaps I have gone wrong in writing the logic. The program is as below.
if X1(i)==a(i) && X2(i)==b(i)
t(i)= a(i)* b(i);
else if X1(i)== a(i) && X2(i)==NaN && X1(i+1)==a(i+1) && X2(i+1)==NaN
t(i)= a(i)* a(i+1);
else if X1(i)== a(i) && X2(i)==NaN && X1(i+1)==NaN && X2(i+1)==b(i+1)
t(i)= a(i)* b(i+1);
else if X1(i)==NaN && X2(i)== b(i)&& X1(i+1)==a(i+1) && X2(i+1)==NaN
t(i)= b(i)* a(i+1);
else if X1(i)==NaN && X2(i)== b(i)&& X1(i+1)==NaN && X2(i+1)==b(i+1)
t(i)= b(i)* b(i+1);
else
t(i)= 0;
end
end
end
end
end
The input is as below. X1=NaN a(2) NaN a(4) a(5) NaN NaN
X2= NaN b(2) b(3) NaN b(5) NaN NaN
i=1:7 and i=8 equals to i=1
The output is as below.
t= 0 c 0 0 d 0 0
But there should be output at t(3) and t(4). Can anybody point out where I went wrong? Thanks
Answers (1)
James Tursa
on 11 Nov 2016
Edited: James Tursa
on 11 Nov 2016
You can't compare to NaN with the == operator, since NaN is not equal to anything (including itself). You must use the isnan function. E.g.,
else if X1(i)== a(i) && X2(i)==NaN && X1(i+1)==a(i+1) && X2(i+1)==NaN
should be
else if X1(i)== a(i) && isnan(X2(i)) && X1(i+1)==a(i+1) && isnan(X2(i+1))
etc.
For example,
>> a = nan
a =
NaN
>> a == nan
ans =
0
>> a == a
ans =
0
6 Comments
See Also
Categories
Find more on Matrix Indexing in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!