Plot from negative infinitive to positive infinative

Question

Tu Nguyen 2022-2-28

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1660555-plot-from-negative-infinitive-to-positive-infinative

回答： Walter Roberson 2022-2-28

clc;
clear all;
close all;
n = (-Inf,Inf)
L = 1;
rectn = rectangularPulse(-1,1,n/L);
w = -8*pi:0.01:8*pi;
for i = 1:numel(w)
    f_FT(i) = trapz(n/L,rectn.*exp(-1i*w(i).*n));
end
figure (1);
subplot(1,2,2);
plot(w, abs(f_FT));
subplot(1,2,1);
plot(n/L,rectn);

Hi all, I want to plot both from from -Inf to Inf. How can I do that in Matlab?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2022-2-28

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1660555-plot-from-negative-infinitive-to-positive-infinative#answer_906520

Suppose that you are able to plot pixels as adjacent "classical" electrons -- 3*10^-15 meters.

Now ask to plot from negative infinity to positive infinity. How large would the plot be?

Well, after only 10^15 the plot would already be 3 metres wide. But 10^15 is a negligible fraction of infinity; there are physical quantities in the range of 10^88 so we should be expecting at least 10^73 meters. But even 10^88 is a negligible fraction of infinity.

If you use any finite size per pixel, then to plot an infinite range, you need an infinitely large physical plot. Even if the size per pixel were only the Planck distance (the distance below which the scale structure of the universe itself breaks down.)