creating a figure that is a segment of another

Question

SonOfAFather 2012-8-29

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/46989-creating-a-figure-that-is-a-segment-of-another

i have a script that gives my figure(1) that graphs a cos wave over 5 sec then i need to section out the first second and have it display in figure(2). when i run my script i get the first figure and the second only displays the x,y cooridinates.

i think i have a problem in the way i sectioned the original vector.

my script looks like this:

clear;
clc;
close all;
% create vector of time values
t = 0.0 : 0.01 : 5.0;
% evaluate function at time points
f = 53*cos(104*pi*t).*exp(-1.35*t);
% plot t vs f(t)
figure(1) 
plot(t,f);
xlabel('t(sec)');
ylabel('f(t)');
%reindex t to exclude the last four seconds
t = 0.0 : 0.01 : 5;
%plot t vs f(t)
figure(2)
plot(t,f(t));
xlabel('t(sec)');
ylabel('f(t)');

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Answer 1

Sven 2012-8-29

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https://ww2.mathworks.cn/matlabcentral/answers/46989-creating-a-figure-that-is-a-segment-of-another#answer_57429

编辑：Sven 2012-8-30

在 MATLAB Online 中打开

I see a few problems:

Your f variable is still based on the original vector of t. You need to run:

f = 53*cos(104*pi*t).*exp(-1.35*t);

again, after you set your new t

Also, you have set t to be the same vector (ie, t = 0.0 : 0.01 : 5; ). I don't think you wanted this.

Finally, in the second figure you are calling:

plot(t,f(t));

but t is still a vector of times, not a vector of indices.

Perhaps you meant the following:

% First figure
t = 0.0 : 0.01 : 5.0;
f = 53*cos(104*pi*t).*exp(-1.35*t);
figure
plot(t,f);
xlabel('t(sec)');
ylabel('f(t)');
% Second figure, using only first 1/5th of t, f
idxs = 1:round(length(t)/5);
figure
plot(t(idxs),f(idxs));
xlabel('t(sec)');
ylabel('f(t)');

By the way, have you tried instead just:

set(gca,'xlim',[0 1])

You can run this after the first plot, and it will "zoom in" on only the first portion from 0 to 1 along the x axis. The rest will be excluded from view.