在matlab 画箭头

非常实用的文章原文地址：在matlab 画箭头作者：纯情小郎君完整见链接http://www.mathworks.com/matlabcentral/fx_files/14056/1/content/arrow3_examples.html

ARROW3  
EXAMPLES   (R13)

Two-dimensional Quiver Plots

Example 1.

Example 2.

Example 3.

Three-Dimensional Quiver Plots

Example 4.

Example 5.

Cone Plots

Example 6.

Example 7.

Feather Plots

Example 8.

Example 9.

Compass Plots

Example 10.

Example 11.

Reference Frames

Example 12.

Example 13.

Example 14.

Named Colors

Example 15.

Update (Modify and Restore)

Example 16.

Two-Dimensional Quiver
Plots

Example 1. (cf.
Joukowski Airfoil Transformation)

t=10*pi/180; u=0.1; v=0.1; r=1.1; tol=8e-2;

s=u+i*v; k=2*r*sin(t); w=exp(i*t);

[x,y]=meshgrid(-2.5:0.1:3.5,-3:0.1:3);

z=x+i*y; z(abs(z-s)<r-tol)=NaN;

f=w*z+exp(-i*t)*r^2./(z-s)+i*k*log(z);

a=0:0.1:2*pi; zc=r*(cos(a)+i*sin(a))+s;

c1=-1.5; c2=2.5; c3=c2-c1;

c=contour(x,y,imag(f),c1:c3/16:c2);

set(gca,'color',0.5*[1 1 1])

hold on, daspect([1 1
1])

fill(real(zc),imag(zc),'y'), colorbar

map=get(gcf,'colormap');

domain=0:1/(size(map,1)-1):1; m=1;
while
m<length(c), n=m+c(2,m);
if
c(2,m)>9, p=c(:,m+1:n)';

   if p(end,1)>p(1,1),
p=flipud(p); end

   
ndx=10:10:length(p);

    p2=p(ndx,:);
p1=p(ndx-3,:);

   
cc=interp1(domain,map,(c(1,m)-c1)/c3);

   
set(gca,'ColorOrder',cc)

   
arrow3(p1,p2,'0o',0.8)
end, m=n+1;
end, hold off

Example 1. Joukowski Airfoil
Transformation

Example 2. (cf.
Quiver)

[x,y]=meshgrid(-1:1/21:1);

z=x.*exp(-x.^2-y.^2);

[c,h]=contour(x,y,z);

set(h,'EdgeColor',0.45*[1 1 1])

ndx=1:3:length(x);

x=x(ndx,ndx); y=y(ndx,ndx); z=z(ndx,ndx);

[u,v]=gradient(z,1/7);

p1=[x(:),y(:)]; u=u(:); v=v(:);

m=abs(u+i*v); % gradient
magnitude

daspect([1 1 1]), set(gca,'color',0.3*[1 1 1])

hold on, colormap
hot, scale=0.4;

arrow3(p1,p1+scale*[u,v],'|',min(1.25*m,0.85))

hold off,
h=colorbar;

set(h,'YTickLabel',num2str(str2num(get(h,...
'YTickLabel'))/scale))

Example 2. Surface
Gradients

Example 3. (cf.
Two-Dimensional Quiver Plots)

[x,y,z]=peaks(-2:0.05:2);

contour(x,y,z,10); h=gca;

ndx=1:4:length(x);

x=x(ndx,ndx); y=y(ndx,ndx); z=z(ndx,ndx);

[u,v]=gradient(z,0.2);

p1=[x(:),y(:)]; u=u(:); v=v(:);

m=abs(u+i*v); % gradient magnitude

hold on, daspect([1 1
1]), scale=0.025;

arrow3(p1,p1+scale*[u,v],'|',0.9*m/max(m))

hold off,
title('Dual
Colormap')

h1=colorbar; h2=copyobj(h1,gcf);

set(h,'color',0.4*[1 1
1],...
'position',get(h,'position')+[0.05 0 0 0])
%
----------------------------------------------------- Right
Colorbar

p=get(h1,'position');

set(h1,'position',[0.87,p(2),0.05,p(4)],...
'YTickLabel',num2str(str2num(get(h1,...
'YTickLabel'))/scale))                           
  % freeze labels

map=colormap; cdata=reshape(map,size(map,1),1,3);

set(get(h1,'children'),'cdata',cdata)             % freeze colors

set(get(h1,'title'),'string','Gradient')
%
------------------------------------------------------ Left
Colorbar

caxis auto, colorbar,
colormap autumn

set(h2,'YAxisLocation','left',...
'position',[0.08,p(2),0.05,p(4)])

set(get(h2,'title'),'string','Contour')

Example 3. Dual Colormap

Three-Dimensional Quiver
Plots

Example 4. (cf.
Quiver3)

[x,y]=meshgrid(-2:0.25:2,-1:0.25:1);

z=x.*exp(-x.^2-y.^2);

surf(x,y,z,'EdgeColor','none')

axis([-2.5 2.5 -1.5 1.5 -1 1]), daspect([1 1 1])

set(gca,'CameraViewAngle',7)

[u,v,w]=surfnorm(x,y,z);

p1=[x(:),y(:),z(:)]; N=[u(:),v(:),w(:)];

hold on

arrow3(p1,p1+0.5*N,'1.5_b')

hold off, colormap
spring

light('position',[-1 -1
-1],'style','local')

light('position',[0 1
1]), lighting gouraud

Example 4. Surface Normals

Example 5. (cf.
Three-Dimensional Quiver Plots)

vx=2; vy=3; vz=10; a=-32; t=(0:.1:1)';

x=vx*t; y=vy*t; z=vz*t+1/2*a*t.^2;

r=[x,y,z]; v=gradient(r')';

axis([0 3 0 4 -10 2]), pbaspect([2 1 1])

hold on, grid on, view([70 18])

arrow3(r,r+v,'b',0.9)

hold off

Example 5. Velocity Vectors

Cone Plots

Example 6. (cf.
Coneplot)

load wind,
wind_speed=sqrt(u.^2+v.^2+w.^2);

xmin=min(x(:)); xmax=max(x(:));

ymin=min(y(:)); ymax=max(y(:));

zmin=min(z(:));

hsurfaces=slice(x,y,z,wind_speed,[xmin,xmax],ymax,zmin);

set(hsurfaces,'FaceColor','interp','EdgeColor','none',...

             'AmbientStrength',0.6)

hold on,
daspect([2,2,1]), view(30,40), axis tight

xrange=linspace(xmin,xmax,8);

yrange=linspace(ymin,ymax,8);

[cx cy cz]=meshgrid(xrange,yrange,3:4:15);

ui=interp3(x,y,z,u,cx,cy,cz);

vi=interp3(x,y,z,v,cx,cy,cz);

wi=interp3(x,y,z,w,cx,cy,cz);

m=sqrt(ui.^2+vi.^2+wi.^2); m=m(:)/30;

p1=[cx(:),cy(:),cz(:)]; p2=[ui(:),vi(:),wi(:)];

hcones=arrow3(p1,p2,'r',m,3*m,'cone');

set(hcones,'DiffuseStrength',0.8)

hold off, axis
off

camproj perspective,
camzoom(1.2)

camlight right,
lighting phong

Example 6. Wind Speed and
Direction

Example 7. (cf.
Vector Field Displayed with Cone Plots)

load wind,
wind_speed=sqrt(u.^2+v.^2+w.^2);

hiso=patch(isosurface(x,y,z,wind_speed,40),...

         'FaceColor','red','EdgeColor','none');

isonormals(x,y,z,wind_speed,hiso)

hcap=patch(isocaps(x,y,z,wind_speed,40),...

         'FaceColor','interp','EdgeColor','none',...

         'AmbientStrength',0.6);

hold on, colormap
hsv, daspect([1,1,1]),
view(65,45)

[f verts]=reducepatch(isosurface(x,y,z,wind_speed,30),0.07);

cx=verts(:,1); cy=verts(:,2); cz=verts(:,3);

ui=interp3(x,y,z,u,cx,cy,cz);

vi=interp3(x,y,z,v,cx,cy,cz);

wi=interp3(x,y,z,w,cx,cy,cz);

m=sqrt(ui.^2+vi.^2+wi.^2); m=m(:)/40;

p1=[cx(:),cy(:),cz(:)]; p2=[ui(:),vi(:),wi(:)];

h1=arrow3(p1,p2,'b',m,3*m,'cone');

xrange=linspace(min(x(:)),max(x(:)),10);

yrange=linspace(min(y(:)),max(y(:)),10);

[cx,cy,cz]=meshgrid(xrange,yrange,3:4:15);

ui=interp3(x,y,z,u,cx,cy,cz);

vi=interp3(x,y,z,v,cx,cy,cz);

wi=interp3(x,y,z,w,cx,cy,cz);

m=sqrt(ui.^2 + vi.^2 + wi.^2); m=m(:)/50;

p1=[cx(:),cy(:),cz(:)]; p2=[ui(:),vi(:),wi(:)];

h2=arrow3(p1,p2,'g',m,3*m,'cone');

hold off, axis
tight, box on

set(gca,'xtick',[],'ytick',[],'ztick',[])

camproj perspective,
camzoom(1.2)

camlight(-45,45), lighting phong

Example 7. Wind Speed and
Direction

Feather Plots

Example 8. (cf.
Feather)

theta=(-90:10:90)'*pi/180;

n=length(theta); p1=[1:n;zeros(1,n)]';

r=2*ones(n,1); [u,v]=pol2cart(theta,r);

plot([1 n],[0 0],'r')

axis([0 20 -2 2]), daspect([8 2 1])

hold on, grid
on

arrow3(p1,p1+[u,v],'r',0.9)

hold off

Example 8. Feather Plot

Example 9. (cf.
Plotting Complex Numbers)

t=(0:0.5:10)'; s=0.05+i; Z=exp(-s*t);

n=length(Z); p1=[1:n;zeros(1,n)]';

plot([1 n],[0 0],'b')

axis([0 22 -1 1]), daspect([8 1 1])

hold on, grid
on

arrow3(p1,p1+[real(Z),imag(Z)],'b',0.8)

hold off

Example 9. Complex Number
Plot

Compass Plots

Example 10. (cf.
Compass Plots)

wdir =[45 90 90 45 360 335 360 270 335 270 335
335];

knots=[ 6 6 8 6  
5  
9  
8  
8   9 10 14 12];

[x,y]=pol2cart(wdir*pi/180,knots);

polar(0,15), axis(15.9*[-1 1 -1 1])

hold on

arrow3(zeros(length(x),2),[x',y'],'r',1.25)

hold off

Example 10. Wind Speed and
Direction

Example 11. (cf.
Compass)

Z=eig(randn(20)); m=abs(Z);

R=ceil(max(m)); r=R+0.3;

polar(0,R), axis(r*[-1 1 -1 1])

hold on

arrow3(zeros(length(Z),2),[real(Z),imag(Z)],'b',1.75*m/R)

hold off

Example 11. Complex Number
Plot

Reference Frames

Example 12. Coordinate Axes

p=[4 2 1]; axis([-6 6 0 5 -1 1])

pbaspect([2 1.5 1]), view(55,15)

hold on

arrow3(repmat([p(1:2),0],4,1),...

[0 p(2) 0;p(1) 0 0;p;0 0 0],'--o',0,0,0.5)

arrow3(zeros(3),diag([7,5,1]),'o')

arrow3([0 0 0],p,'2.5s',1.5,[],0)

hold off, axis
off, camlight
left

set(gca,'CameraViewAngle',4)

text(7.1,0,0,'X'),
text(0,5.05,0,'Y')

text(0,0,1,'Z','VerticalAlignment','bottom',...
'HorizontalAlignment','center')

Example 12. Coordinate Axes

Example 13. Eigenvectors

n=500; % generate test data

newz=[ 1 1 1]/sqrt(3);

newy=[ 0 -1 1]/sqrt(2);

newx=cross(newy,newz);

R=[newx;newy;newz]; % rotation
matrix

U=randn(n,3)*diag([1,2,3])*R;

u=U(:,1)+10; v=U(:,2)+20; w=U(:,3)+30;
% plot eigenvectors with mean
origin

plot3(u,v,w,'r.')

axis([0 20 10 29 20 40]), daspect([1 1 1])

view([-70,15]), set(gca,'CameraViewAngle',8)

hold on, grid
on

mu=repmat(mean([u,v,w]),3,1);

[V,D]=eig(cov([u,v,w]));

p=9*V'+mu;

arrow3(mu,p,[],1.25,[],0)

p=p+ones(3);

text(p(1,1),p(1,2),p(1,3),'bfU')

text(p(2,1),p(2,2),p(2,3),'bfV')

text(p(3,1),p(3,2),p(3,3),'bfW')

hold off

Example 13. Eigenvectors

Example 14. (cf.
Frenet)

z=(0:2/99:2)'; t=2*pi*z; r=2+z;

x=r.*cos(t); y=r.*sin(t);

R=[x,y,z]; dR=gradient(R')';

m=repmat(sqrt(sum(dR.*dR,2)),1,3);

T=dR./m; dT=gradient(T')';

m=repmat(sqrt(sum(dT.*dT,2)),1,3);

N=dT./m; B=cross(T,N);

plot3(x,y,z,'color',0.5*[1 1 1])

axis([-4 4 -4 4 0 2.5])

hold on, grid
on, pbaspect([1 1
1])

set(gca,'CameraViewAngle',7)

plot3(0,0,0,'r'),
plot3(0,0,0,'color',[0
0.5 0])

plot3(0,0,0,'b')

legend('Curve','Tangent','Normal','Binormal',2)

ndx=1:4:length(x); R=R(ndx,:);

arrow3(R,R+1.4*T(ndx,:),'r',0.9)

arrow3(R,R+1.4*N(ndx,:),'e',0.9)

arrow3(R,R+0.4*B(ndx,:),'b',0.9)

hold off,
view(-50,5)

set(gcf,'renderer','zbuffer')

Example 14. Frenet Frames

Named Colors

Example 15. Named Color Table

arrow3('colors',0.4) % 24 named colors with 44 adjustable
shades

Example 15. Named Color
Table

Color Equivalencies
ColorOrder            Arrow3	Simulink          Arrow3
Color1		Blue	LightBlue		aZure
Color2		Evergreen	DarkGreen		Asparagus
Color3		Red	Orange		kumQuat
Color4		Sky blue	Gray		Light gray
Color5		Violet
Color6		Pear
Color7		Dark gray