how to scale arrows

Question

MAJED 2014-6-24

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https://ww2.mathworks.cn/matlabcentral/answers/137442-how-to-scale-arrows

回答： Adam Danz 2024-4-26

I have this code for a vector field, the arrows keep getting crazier no mater what i do, can some one plese tell me how do i make them look nice and organized and same size

t1 = linspace(-1,500,10);
y1 = linspace(140,160,10);
[T,Y]=meshgrid(t1,y1);
DY=TribMod4(T,Y); DT=ones(size(DY));
scale =  1./sqrt(DT.^2+DY.^2);
p1=quiver(T,Y, 0.01.*DT, 0.001.*DY);
set(p1,'AutoScale','on', 'AutoScaleFactor', 0.08)
axis([-5 500 140 160])
hold on
[t,y]=ode45(@TribMod4,[0:0.51:900],147.971);
plot(t,y,'r')
ylabel('y')
xlabel('time (t)')
title('Direction field of function(2) with b=0.005')

thanks

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Answer 1

Star Strider 2014-6-25

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https://ww2.mathworks.cn/matlabcentral/answers/137442-how-to-scale-arrows#answer_142369

在 MATLAB Online 中打开

You can turn autoscaling off by commenting the ‘set’ statement so it will not execute and instead calling quiver with:

quiver(x, y, dxda, dyda, 0)

The arrow lengths are controlled by the (u,v) vectors in the quiver documentation (here the (dxda,dyda) vectors), so while you can turn off autoscaling (that normally keeps the arrows from overlapping), according to the documentation and some of my experiments, you would have to control their lengths with (u,v).

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Answer 2

Adam Danz 2024-4-26

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https://ww2.mathworks.cn/matlabcentral/answers/137442-how-to-scale-arrows#answer_1448761

Quiver scaling can be tough to understand. We recently added the ScaleFactor property (R2024a) to help out. See this answer for 3 ways to control the scale of quiver arrows.

https://www.mathworks.com/matlabcentral/answers/1850583-how-can-i-set-the-dimension-of-the-arrow-in-a-quiver-plot#answer_1448756