Define a variable without assigning a value

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Rayan EL-KHOLDI
Rayan EL-KHOLDI 2020-5-24
评论： Matt J 2024-2-7
Hi,
I want to create a variable m without assigning it a value, and do a calculation with it, is it possible?
Thnak you in advance,
R

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回答（2 个）

Matt J
Matt J 2020-5-24
Perhaps you are trying to do symbolic computations,
https://www.mathworks.com/help/symbolic/performing-symbolic-computations.html
If so, you need the Symbolic Math Toolbox.
  2 个评论
Jo Do
Jo Do 2022-11-9
Thank you so much. Just created an account to thank you.
Matt J
Matt J 2022-11-9
You are quite welcome. Please Accept-click the answer if it was useful to you.

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Tadios
Tadios 2024-2-7
Ran in:
clc
clear
% close
snr = 20:5:60;
datanum = 10000;
M = 4;
K = [4, 10];
invber = zeros(2,length(snr));
reginvber = zeros(2,length(snr));
for ind1 = 1:1:length(snr)
disp(['Signal to noise ratio: ' num2str(snr(ind1)) ' dB'])
invtransmission
ber = invtransmission(snr, K, datanum);
invber4 = invtransmission(snr(ind1),K(1),datanum);
reginvber4 = reginvtransmission(snr(ind1),K(1),datanum);
invber10 = invtransmission(snr(ind1),K(2),datanum);
reginvber10 = reginvtransmission(snr(ind1),K(2),datanum);
invber(:,ind1) = [invber4; reginvber4];
reginvber(:,ind1) = [invber10; reginvber10];
end
Signal to noise ratio: 20 dB
Unrecognized function or variable 'invtransmission'.
invber;
reginvber;
figure
semilogy(snr,invber(1,:),'r--x','linewidth',1.5)
hold on
semilogy(snr,invber(2,:),'r-d','linewidth',1.5)
semilogy(snr,reginvber(1,:),'b-+','linewidth',1.5)
semilogy(snr,reginvber(2,:),'b-*','linewidth',1.5)
xlabel('rho (dB)');ylabel('BER')
legend('4x4 Channal Inversion','4x4 Regularized Channal Inversion',...
'10x10 Channal Inversion','10x10 Regularized Channal Inversion')
how to fix the problem " invtransmission4 = invtransmission(snr(ind1),K(1),datanum)"
  2 个评论
Walter Roberson
Walter Roberson 2024-2-7
The line you indicated as having a problem, does not appear in the code posted.
Functions invtransmission and reginvtransmission are not defined.
Matt J
Matt J 2024-2-7
@Tadios You've posted as an answer that doesn't appear to address the OP's question, or to be related to it in any way. I will delete it soon, but invite you to repost as a separate question.

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