Complex matrix , make certain elements of real and imaginary as zero in a single line without storage
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Suppose I have the following complex matrix
s = rng;
A = complex(randn(5,5),randn(5,5));
T = 0.15
How do I make both the real part corresponding to less than T equal to zero and how do I make imaginary part less than T equal to zero in the same step It is like making the following in one single line
1. realA = real(A);
2. imagA = imag(A);
3. realA(realA<T) = 0
4. imagA(imagA<T) = 0
5. A = complex(realA,imagA)
How do I convert the five steps above in a single line only using A , and no storing of real part of A and imaginary part of A in realA and imagA respectively.
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Answers (1)
Walter Roberson
on 29 Aug 2018
A = complex( real(A) .* (real(A) >= T), imag(A) .* (imag(A) >= T));
However, this will fail for real or complex part equal to -infinity, creating NaN in those locations, because 0 (false) times infinity is NaN instead of 0.
11 Comments
Walter Roberson
on 30 Aug 2018
If your goal is FPGA then give up on writing as single statement and just do in-place for loop.
Walter Roberson
on 31 Aug 2018
for k=1:length(A)
Ar = real(A);
Ai = imag(A);
if Ar < T; Ar = 0; end
if Ai < T; Ai = 0; end
A(K) = complex(Ar,Ai);
end
Extra storage: minimal.
Multiplications: none.
If you want to improve performance at the expense of additional die space, have your compiler do automatic loop unrolling.
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