Save Complex vector from Matlab to text file - matlab

Question

I generate a vector of complex numbers with Matlab and I want to save that vector into text file (.txt) to use it as input in my C code so the complex vectors looks like :
y = zeros(1,N);
for n = 1:N
y(n) = exp(-1i*(n-1)*k*d*sind(Qtgt));
end
picture
So I tried the functon dlmwrite to save the vector into text file :
dlmwrite('data.txt', y, 'delimiter','\n','newline', 'pc')
the vector stored like this :
picture 2
but I want it to be stored in this way : picture3
every complex number should stored in new line and the real part, the imaginary part should be separated with coma Any idea please ?

Answer 1

lifay:
This has a very simple fix: In your callout to dlmwrite, replace the y input for [real(y'),imag(y')]
Here's my attempt:
N = 10;
y = zeros(1,N);
for n = 1:N
y(n) = exp(-1i*(n-1));
re = real(y(n));
im = imag(y(n));
fprintf('%6.10f,%6.10f\n',re,im)
end
filename = 'output';
dlmwrite(filename,[real(y)',imag(y')],'precision',16)
Output to the above (granted I have a slightly different formula) on my end is:
The reason the output is given as shown by your "Picture 2" is that y is a row vector. Unless explicitly "told" otherwise by the programmer, MATLAB assumes arrays to be row vectors. MATLAB's dlmwrite output emulates the shape of the input array, in this case, a row vector, therefore, picture 2 is what you get. To get the output of picture 3, you must input a rectangular matrix. I achieve this above by concatenating two(2) row vectors that were transposed into column vectors. To perform the transposition use the ' operator as shown. Notice that I transpose the output of the real function and then the input to the imag function. These functions also emulate the shape of their respective input arrays into their respective output arrays. So, [real(y)',imag(y')] has the same effect as [real(y'),imag(y')].
Also, don't forget to specify the "precision" parameter to ensure that dlmwrite stores all the digits possible, if unspecified, dlmwrite will truncate the numbers and introduce truncation error into your further calculations in C.