I think i have problem with pause command
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Hello dudes, i make a small animation on matlab about a body that start from Y=0 with initial velocity. My problem is that on the paper maths shows that the total time of the animation will be 4sec but when i run the programm does seem to be same running time. I think that my error is on the pause command but i can't solve it
tspan =0:0.01:4;
y0 = 0;
[t,y] = ode45(@(t,y) -10*t+20, tspan, y0);
plot(t,y)
grid on
x1=[0, 0, 1, 1];
y1=[0, 0.5, 0.5, 0];
x2=[0, 0, 10, 10];
y2=[0, 0.01, 0.01, 0];
fill(x2,y2,'black');
hold on
axis([0 10 -5 25])
grid on
time=0
z=1
while time<=400
time=time+1;
ypsos=y(z)
p=fill(x1,y1+ypsos,[0 0.41 0.53])
pause(0.009)
drawnow
delete(p);
z=z+1;
end
采纳的回答
Walter Roberson
2020-10-8
It is not obvious that you are filling the area that you would want to fill, but this at least finished quickly enough.
tspan =0:0.01:4;
y0 = 0;
[t,y] = ode45(@(t,y) -10*t+20, tspan, y0);
plot(t,y);
axis([0 10 -5 25])
grid on
hold on
drawnow();
x1=[0, 0, 1, 1];
y1=[0, 0.5, 0.5, 0];
x2=[0, 0, 10, 10];
y2=[0, 0.01, 0.01, 0];
fill(x2,y2,'black');
grid on
for time = 1 : 400
ypsos=y(time);
p=fill(x1,y1+ypsos,[0 0.41 0.53]);
pause(0.009)
drawnow
delete(p);
end
2 个评论
Walter Roberson
2020-10-9
If the idea is "real time" animation, then:
start = tic;
for time = 1 : 400
ypsos=y(time);
p=fill(x1,y1+ypsos,[0 0.41 0.53]);
if time ~= 400
pause(y(time+1) - toc(start));
end
delete(p);
end
Outputs will tend to be slightly late, but there should not be any cumulative drift as the time is compared to the start time rather than assuming that we started this round on time.
Walter Roberson
2020-10-9
cla reset
tspan =0:0.01:4;
y0 = 0;
[t,y] = ode45(@(t,y) -10*t+20, tspan, y0);
plot(t,y)
grid on
x1=[0, 0, 1, 1];
y1=[0, 0.5, 0.5, 0];
x2=[0, 0, 10, 10];
y2=[0, 0.01, 0.01, 0];
fill(x2,y2,'black');
hold on
axis([0 10 -5 25])
grid on
start = tic;
p = fill(x1, y1, [0 0.41 0.53]);
for time = 1 : 400
ypsos=y(time);
p.YData = y1+ypsos;
pause(t(time+1)-toc(start));
end
toc(start)
更多回答（2 个）
Luciano Garim
2020-10-8
To solve your problem, you may use the conditional command "if" and "return". Try to execute this code now.
tspan =0:0.01:4;
y0 = 0;
[t,y] = ode45(@(t,y) -10*t+20, tspan, y0);
plot(t,y)
grid on
x1=[0, 0, 1, 1];
y1=[0, 0.5, 0.5, 0];
x2=[0, 0, 10, 10];
y2=[0, 0.01, 0.01, 0];
fill(x2,y2,'black');
hold on
axis([0 10 -5 25])
grid on
time=0
z=1
while time<=1000
time=time+1;
if time>400
return;
end
ypsos=y(z)
p=fill(x1,y1+ypsos,[0 0.41 0.53])
pause(0.009)
drawnow
delete(p);
z=z+1;
end
I hope helped you!
1 个评论
Walter Roberson
2020-10-8
return is not needed. If you want to stop at 400, just change the while limit. if / return approach here has nothing to recommend it over the approach the original person used.
sim ts
2020-10-9
0 个投票
3 个评论
Walter Roberson
2020-10-9
编辑：Walter Roberson
2020-10-9
pause() has no effect on the calculation other than to delay it.
pause() has an effect on the plotting, in that it has the side effect of triggering immediate drawing.
WIth the code I posted, you get an animation of a bar floating upwards and back downwards.
when i measue the time it doesn't corresponding on my result
How are you measuring time?
Are you trying to animate in "real time", something displaying in the screen at elapsed time according to t(time) ?
sim ts
2020-10-9
sim ts
2020-10-9
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