How to plot these equations ?
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Hello
I'm trying to plot these polynomials shown in the image, but I keep receiving errors and I'm not if my code is correct of not. Could you please help ?
regards
clear all
close all
clc
%%
Fs = 1000; % Sampling frequency
T = 1/Fs; % Sampling period
L = 1024; % Length of signal
t = 2*(0:L-1)*T; % Time vector
x = 0;
c = 1+i;
P(1) = 1;
Q(1) = 1;
P(2) = P(1) + exp(i*(2^(0))*t)*Q(1);
Q(2) = P(1) - exp(i*(2^(0))*t)*Q(1);
P(3) = P(2) + exp(i*(2^(1))*t)*Q(2);
Q(3) = P(2) - exp(i*(2^(1))*t)*Q(2);
P(4) = P(3) + exp(i*(2^(2))*t)*Q(3);
Q(4) = P(3) - exp(i*(2^(2))*t)*Q(3);
for m=1:16
x = x +c*exp(i*2*pi*m*t).*P(m);
end
figure
subplot(2,2,1)
plot(t,x)
title('signal')
6 个评论
Image Analyst
2022-1-23
编辑：Image Analyst
2022-1-23
What is this "x" that you're overwriting on each iteration of the for loop? I thought you wanted to compute p and q, not x.
And MATLAB thinks i is a variable. So if you want to use it as a variable you need to use
i = sqrt(-1);
or else use a 1 in front of it: 1i
Matt J
2022-1-23
They don't look like polynomials to me. Also, they are complex-valued, so what does it mean to "plot" them? If you want to plot their absolute value, do plot(t,abs(x)).
Mohamed Ahmed
2022-1-23
Mohamed Ahmed
2022-1-23
Matt J
2022-1-23
That is correct. P(2) is a scalar location. It cannot hold a vector
Mohamed Ahmed
2022-1-23
采纳的回答
Change P(m) to P{m} and Q(m) to Q{m} everwhere.
Fs = 1000; % Sampling frequency
T = 1/Fs; % Sampling period
L = 1024; % Length of signal
t = 2*(0:L-1)*T; % Time vector
x = 0;
c = 1+i;
P{1} = 1;
Q{1} = 1;
for m=2:16
P{m} = P{m-1} + exp(1i*(2^(m-2))*t).*Q{m-1};
Q{m} = P{m-1} - exp(1i*(2^(m-2))*t).*Q{m-1};
end
for m=1:16
x = x +c*exp(1i*2*pi*m*t).*P{m};
end
whos x
4 个评论
Mohamed Ahmed
2022-1-23
Matt J
2022-1-23
Make sure you're using my latest iteration of the code.
Mohamed Ahmed
2022-1-23
编辑：Mohamed Ahmed
2022-1-23
Yes, It worked, I also plotted the magnitude and phase spectrum of the signal.
Is this plot considered a flat spectrum ?
Thank you :)
Matt J
2022-1-23
I'm glad it worked, but please Accept click the answet to indicat so.
Whether it's to be considered flat is probably subjective...
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