struggeling with the quiver function

My name is Hidde and i am working on a university project. I need to plot arrows inbetween serveral datapoints. I tried using the quiver function but the headwith gets

all weird. This is because my y axis runs from 0 to 500 and my x axis runs from 0 12. Does somebody know how to fix this? i want arrows with filled arrowheads that are all

the same size and shape regardless of arrow length ect.

i attached the relevant data and matlab files.

[Hidde Kemperink]

i have marked 2 example data points (1 and 2) in the end of the T_S_diagram code. the first flow should go from 1 to 2 to 3 to 4 and finnaly to 5

[Adam Danz]

The term "quiver" isn't mentioned anywhere in either m-file. Where are you applying the quiver function?

Also, make it very easy for us to help you by reducing the amount of work we need to do to understand the problem. There are more than 3900 lines of code between your two m-files.

[Hidde Kemperink]

Hey adam, thanks for your reply. I tried using it between the first 2 datapoints i marked. But the arrow heads get scaled really weird so i removed it. This is due to the axis of my plot being so different

[Hidde Kemperink]

The XSteam file is something provided by my university. It contains thermodynamic data i need and its not to be changed. Its just to run my diagram file

[Hidde Kemperink]

All i am trying to do is create a vector between 2 data points. But the axis are so different that the arrowhead scaling of quiver gets messed up

[Adam Danz]

I see what you're describing. A much simpler way to demonstrate this is,

clf()
axes()
endPoint = [5.8, 175]; % [x,y] of arrow end point
headPoint = [7, 200]; % [x,y] of arrow head
plot([endPoint(1),headPoint(1)],[endPoint(2),headPoint(2)],'r*')
xlim([0,12])
ylim([0,500])
grid on 
hold on

uv = headPoint - endPoint; % [x,y] distance
quiver(endPoint(1),endPoint(2),uv(1), uv(2),'b-','AutoScale','off')

●

This is a difficult problem because the quiver() function does not provide a way to change the arrow heads other than to turn them off. The annotation function with the arrow lineType is an alternative but problematic because it only receives corrdinates normalized to the figure (not the axes) so you'd need to compute the normalized position of the arrow and never change the axis limits or ratio.

Answer 1

[Adam Danz]

Given the problem described in my comment above, the easiest solution in my opinion is to replace the arrow with a different marker such as a circle and then define which end point of the vector the marker represents.

Here are two examples.

clf()
subplot(2,1,1)
endPoint = [5.8, 175]; % [x,y] of arrow end point
headPoint = [7, 200]; % [x,y] of arrow head
plot([endPoint(1),headPoint(1)],[endPoint(2),headPoint(2)],'r*')
xlim([0,12])
ylim([0,500])
grid on
hold on
uv = headPoint - endPoint; % [x,y] distance

quiver(endPoint(1),endPoint(2),uv(1), uv(2),'b-o','AutoScale','off','ShowArrowHead','off')
text(0,0,'o indicates base of vector in o---', 'VerticalAlignment','bottom')
subplot(2,1,2)
plot([endPoint(1),headPoint(1)],[endPoint(2),headPoint(2)],'r*')
xlim([0,12])
ylim([0,500])
grid on
hold on
uv = endPoint - headPoint; % [x,y] distance

quiver(headPoint(1),headPoint(2),uv(1), uv(2),'b-o','AutoScale','off','ShowArrowHead','off')
text(0,0,'o indicates head of vector in ---o', 'VerticalAlignment','bottom')