Value not multiplying by -1
1 view (last 30 days)
Show older comments
I have a nested if statement which works as it is supposed to until the last iteration.
Does anyone know why it is not multiplying the last value by -1?
w = x_0 % zero vector
k = 0 % zero value
i=1 % initial value for count
j=-1 % coefficient
for i = 1:n
if Raw_Data(i,2) == Raw_Data (i,3)
fprintf ('ERROR!!!!!)
else if Raw_Data(i,3) == val
w(i,1) = Raw_Data(i,4)
else if Raw_Data(i,2) == val
w(i,1) = j* Raw_Data(i,4)
% Rationalisation Not Working
else w(i,1)= j* Raw_Data(i,4)
end
end
end
i=i+1
end
Accepted Answer
Thorsten
on 7 Apr 2015
Edited: Thorsten
on 7 Apr 2015
I would suggest to avoid the loop and use logical indexing:
ind = Raw_data(i,3) == val;
w(ind) = Raw_data(:,4);
w(~ind) = j*Raw_data(:,4);
if any(Raw_Data(i,2) == Raw_Data (i,3))
error('values in column 2 and 3 are identical.')
end
Note that in your code
else if Raw_Data(i,2) == val
is not needed, because
w(i,1) = j* Raw_Data(i,4)
in any case.
And if w is a vector, w(i) is the same as w(1,i).
0 Comments
More Answers (2)
Ingrid
on 7 Apr 2015
in a for loop there is no need to increment the i so just leave out
i = i+1
as this is done automatically.
Also do not use the i as this can be confusing when using imaginary numbers, better practice is to use ii or something completly else (for example counter )
It is not clear why there is an
else if Raw_Data(i,2) == val
when you perform the same function regardless of true/false of this expression
See Also
Categories
Find more on Resizing and Reshaping Matrices in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!