Square Root Complex Numbers
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Hi
I'm new to Matlab. I have a matrix of data for example 1.04,-5.84,-5.84,8.54 etc. As you can see its a mixture of positive and negative values. I have to square root all the numbers and then add the square root up.
I get an output like this: 0 + 0.2572i 1.4758 0 + 1.0258i 0 + 1.0297i .... etc
How can I add these up because when I do the sum total is displayed like so: 24.1589 +25.8258i I was expecting a real number such as 25.0414 why is it formatted like this. I am new to matlab so not sure what I need to do, works fine if my data has no negative numbers so I assume it's to do with that.
Thanks
3 个评论
Walter Roberson
2013-3-9
Suppose your entire data was just (say) -2 . Then what would you want as the result of the operation?
Josh
2013-3-9
Youssef Khmou
2013-3-9
real parts are summed separately from imaginary parts , if you want add both Real and Imag sumsthen try :
r=rand(10);
p=sqrt(r);
S=sum(real(p(:)))+sum(imag(p(:)));
回答（2 个）
Youssef Khmou
2013-3-9
hi Josh,
the square root of <0 number is complex number , if you only want the real part use "real" function, but if you want imaginary part, use "imag" function, and for the modulus you can use "abs" function , example :
r=randn(10);
p=sqrt(r);
Real_part=sum(real(p(:)));
Imag_part=sum(imag(p(:)));
Modul_part=sum(abs(p(:)));
Walter Roberson
2013-3-10
编辑：Walter Roberson
2013-3-10
To get the results you indicate you want (which are not the results one would normally want when taking the square roots of negative numbers),
sum(sqrt(r(r>0))) - sum(sqrt(-r(r<0)))
Remember, sqrt(-A) is not -sqrt(A) but is instead 1i * sqrt(A) where 1i indicates sqrt(-1)
5 个评论
Yogan Sganzerla
2019-8-6
Dear Walter,
I have a matrix M with complex number, as u can see the image below.
I would like to know the correct way to extract the squere root of M.
Could I use sqrm(M)?
Thank you for your attention.
Torsten
2019-8-6
You want to get the matrix A with A^2 = M or with A.^2 = M ?
Yogan Sganzerla
2019-8-6
编辑：Yogan Sganzerla
2019-8-6
A^2 = M
Torsten
2019-8-6
A = sqrtm(M)
Yogan Sganzerla
2019-8-6
Perfect! Thank you very much.
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2019-8-6
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