Duplicate Points In Overlapping Section of Two Overlapping Spheres
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I have two overlapping spheres, and I am using the Monte Carlo method to calculate the volume of the combined spheres. Everything is working except for one part. I need to find a way to NOT double count points placed in the overlapping region so that I can correctly calculate the ratio of points inside the spheres to the points outside in the cube. Can someone help me with how not to double count points in the overlapping region? Here is my code so far:
clc
clear all
S=input('Number of Simulations: ');
N=input('Number of Points: ');
fileID = fopen('Volume.txt','w');
for k = 1:S
[X, Y, Z]=sphere;
a = [1 1 1 1.2; 2.293,1,1,1.8];
%Draw sphere #1
figure('color','white');
s1=surf(X*a(1,4)+a(1,1), Y*a(1,4)+a(1,2), Z*a(1,4)+a(1,3),'FaceColor', [1 1 1],'edgecolor','none','FaceAlpha',0.6);
light
axis equal
set(gca,'Color','k')
hold on
%Draw sphere #2
s2=surf(X*a(2,4)+a(2,1), Y*a(2,4)+a(2,2), Z*a(2,4)+a(2,3),'FaceColor', [0 1 0],'edgecolor','none','FaceAlpha',0.5);
daspect([1 1 1])
view(30,10)
xlabel('x')
ylabel('y')
zlabel('z')
x1range1 = -0.2;
x1range2 = 4.2;
y1range1 = -0.9;
y1range2 = 2.9;
z1range1 = -0.9;
z1range2 = 2.9;
hit1 = 0; %Points inside spheres
hit2 = 0;
for i = 1:N
%Define Box Range and Randomize Points
x = (x1range2-x1range1).*rand(N,1)+x1range1;
y = (y1range2-y1range1).*rand(N,1)+y1range1;
z = (z1range2-z1range1).*rand(N,1)+z1range1;
x1=x-1;
y1=y-1;
z1=z-1;
r1=sqrt(x1.^2+y1.^2+z1.^2);
x2=x-2.293;
y2=y-1;
z2=z-1;
r2=sqrt(x2.^2+y2.^2+z2.^2);
ii = r1<=1.2;
jj = r2<=1.8;
hit1 = sum(ii);
hit2 = sum(jj);
plot3(x(ii), y(ii), z(ii), 'w+');
%plot3(x(~ii), y(~ii), z(~ii), 'r+');
plot3(x(jj), y(jj), z(jj), 'g+');
drawnow
end
SpherePercentVolume = (hit1+hit2)/N;
Volume = ((x1range2-x1range1)*(y1range2-y1range1)*(z1range2-z1range1))*SpherePercentVolume
fprintf(fileID,'%6.3f\r\n',Volume);
end
fclose(fileID);
load Volume.txt
average = mean(Volume);
stdev = std(Volume);
fileID = fopen('AvgVolume.txt','w');
fprintf(fileID,'%6s','Average Volume: ');
fprintf(fileID,'%6.3f\r\n',average);
fprintf(fileID,'%6s','Standard Deviation: ');
fprintf(fileID,'%6.3f',stdev);
2 个评论
David Goodmanson
2019-1-16
Hi Kelly,
I don't know what the for loop from 1 to N does, but aside from that there are various ways to accomplish this with some boolian operations.
ii & jj indexes the points in both spheres, which you can use to correct for double counting.
ii & ~jj indexes the points in sphere 1 and not in sphere 2, etc.
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