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
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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
回答(1 个)
James Tursa
2016-11-11
编辑:James Tursa
2016-11-11
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
另请参阅
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