plotting 3D vector field in MATLAB in many different ways

Recently I read post from Dr. Doug Hull's blog:

http://blogs.mathworks.com/videos/2009/10/23/basics-volume-visualization-19-defining-scalar-and-vector-fields/

I liked this video tutorial so much and I really felt that should finish the 'homework' assigned at the very end. So I spent sometime on it and here are my code and figures.

clear;close all;clc;
load wind
speed=sqrt(u.*u+v.*v+w.*w);
%%
figure(1)
scatter3(x(:),y(:),z(:),[],speed(:))
%%
figure(2)
slice(x,y,z,speed,[],[],[5 10 15])
zlim([0 20])
%%
figure(3)
[xs, ys]=meshgrid(60:140, 20:60);
zs=20*ys./xs;
slice(x,y,z,speed,xs,ys,zs)
%%
figure(4)
contourslice(x,y,z,speed,[],[],[5 10 15],20)
zlim([0 20])
view(3)

%%
figure(5)
fv1=isosurface(x,y,z,speed, 10);
fv2=isosurface(x,y,z,speed, 20);
fv3=isosurface(x,y,z,speed, 30);
h1=patch(fv1);
h=patch(fv2);
h3=patch(fv3);
set(h1,'FaceColor',[1, 0.6, 0])
set(h1,'EdgeColor','none')

set(h,'FaceColor',[0, 0.5, 0.5])
set(h,'EdgeColor','none')

set(h3,'FaceColor',[1, 0.4, 1])
set(h3,'EdgeColor','none')
camlight;
lighting gouraud
view(3)

%% 
figure(6)
quiver3(x,y,z,u,v,w);

%%
figure(7)
[cx,cy,cz]=meshgrid([70 80 90 100 110 120], [20 30 40 50 60],[0 5 10 15]);
coneplot(x,y,z,u.*100,v.*100,w.*100,cx,cy,cz,speed);
% set(h, 'edgecolor','none')
shading interp;
view(3)

%%
figure(8)
streamline(x,y,z,u,v,w,80,40,10)
hold on
plot3(80,40,10, 'bo')
view(3)

%%
figure(9)
[sx,sy,sz]=meshgrid(100,[20 30 40], [5 10]);
streamline(x,y,z,u,v,w,sx,sy,sz)
hold on
plot3(sx(:),sy(:),sz(:),'bo')
view(3)

%%
figure(10)
streamslice(x,y,z,u,v,w,[],[],1)
view(3)

%%
figure(11)
streamtube(x,y,z,u,v,w,sx,sy,sz)
shading interp;
view(3)
%%
figure(12)
h=streamribbon(x,y,z,u,v,w,sx,sy,sz);
shading interp;
view(3)

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Give curves random color, just for fun

A few days ago, I drew some curves on a same plot. And now I want to randomize the curve color.

Because the color syntax can be expressed as letters such as k, g, b etc. and also as a three element row, which indicate the RBG mode, such as [1, 0, 1], [0.1,0.7, 0.4] and so on.

So here I wrote a M-file to randomize the color and plot 10 curves in each subplot.

%this code produce a three element row
%which can be used to specify a random color
%created on 02/15/2010
function rndclr=f()
rndclr=[rand, rand, rand];
%this code draws some curves
%of random color
clf
t=0:0.01:100*pi;
for j=1:9
for i=1:10
hold all;
x=(i+2)*cos(t/i)+cos((i-1)*t);
y=i*sin(t/i)+sin((i-3)*t);
subplot (3,3,j);
plot(x,y,'color',rndclr)
axis('equal')
axis off
end
end

And here is the figure:

Yahoo META Tag

I'm not sure if this will work or not. Let's see!

Factorial in Matlab

To calculate the factorial of n in Matlab, that's simple:

factorial (n)

will do it.

plotting some curves, just for fun

%this code draws some curves
clf
t=0:0.01:100*pi;
for i=1:10
    hold all;
x=(i+2)*cos(t/i)+cos((i-1)*t);
y=i*sin(t/i)+sin((i-3)*t);
plot (x,y,'red')
end
axis('equal')

3D Random walk

% random walk
x=[];
y=[];
z=[];
x(1)=0;
y(1)=0;
z(1)=0;
for i=1:20000
J=rand*6;
if J<1>1)&(J<2)>2)&(J<3)>3)&(J<4)>4)&(J<5)
x(i+1)=x(i);
y(i+1)=y(i);
z(i+1)=z(i)+1;
else
x(i+1)=x(i);
y(i+1)=y(i);
z(i+1)=z(i)-1;
end
end

plot3(x,y,z)

Result:

2D Random walk program

Why I want to do this?
http://en.wikipedia.org/wiki/Random_walk

Here's the code I wrote:

% random walk
x=[];
y=[];
x(1)=0;
y(1)=0;
for i=1:100000
J=rand;
if J<0.25
x(i+1)=x(i)+1;
y(i+1)=y(i);
elseif (J>0.25)&(J<0.5)
x(i+1)=x(i)-1;
y(i+1)=y(i);
elseif (J>0.5)&(J<0.75)
x(i+1)=x(i);
y(i+1)=y(i)+1;
else
x(i+1)=x(i);
y(i+1)=y(i)-1;
end
end

plot(x,y)

And here are the figure I got:

Pictures of magic matrix (50x50)

Plotmatrix: This one is 5x5

area:

bar:

comet:

compass:

contour:

contourf:

image:

imagesc:

loglog:

mesh:

pcolor:

plot:

polar:

ribbon:

semilogx

semilogy

spy

stairs

stem3

stem

surf