如何提高matlab的速度

Question

这是我的matlab代码。它运行速度太慢，我不知道如何改进它。

你能帮我提高速度吗？

我想要做的是创建一些随机点，然后删除随机点，使它们类似于我的目标点。

syms Dx Dy p q; 

a = 0; 

num = 10; 
x = rand(1,num); 
y = rand(1,num); 
figure(1) 
scatter(x,y,'.','g') 

%num_x = xlsread('F:\bin\test_2');% num 1024 
%figure(2) 
%scatter(num_x(:,1),num_x(:,2),'.','r'); 

q = 0; 
num_q = 10; 

x_q = randn(1,num_q); 
y_q = randn(1,num_q); 

%figure(2) 
hold on; 
scatter(x_q,y_q,'.','r') 

for i = 1:num_q; 
    for j = 1:num_q; 
     qx(i,j) = x_q(i) - x_q(j); 
     qy(i,j) = y_q(i) - y_q(j);  
     %qx(i,j) = num_x(i,1) - num_x(j,1); 
     %qy(i,j) = num_x(i,2) - num_x(j,2); 
     %d~(s(i),s(j)) 
     if ((qx(i,j))^2+(qy(i,j)^2))> 0.01 % find neighbours 
      qx(i,j) = 0; 
      qy(i,j) = 0; 
     end 
    end 
end 

for i = 1:num_q; 
    for j = 1:num_q; 
     if qx(i,j)>0&&qy(i,j)>0 
     q = q + exp(-(((Dx - qx(i,j))^2)+((Dy - qy(i,j))^2))/4);%exp(-(((Dx - qx(i,j))^2)+((Dy - qy(i,j))^2))/4); 
     end 
    end 
end 

%I = ones(num,num); % I(s) should from a grayscale image 
%r = 1./sqrt(I); 
for s = 1:100; 

for i = 1:num; 
    for j = 1:num; 
     dx(i,j) = x(i) - x(j); 
     dy(i,j) = y(i) - y(j); 
     %d~(s(i),s(j)) 
     if ((dx(i,j))^2+(dy(i,j)^2))> 0.05 % delta p, find neighbours 
      dx(i,j) = 0; 
      dy(i,j) = 0; 
     end 
    end 
end 

p = 0; 
for i = 1:num; 
    for j = 1:num; 
     if dx(i,j)>0&&dy(i,j)>0 
     p = p + exp(-(((Dx - dx(i,j))^2)+((Dy - dy(i,j))^2))/4); 
     end 
    end 
end 

p = p - q; 
sum = 0; 
for i = 1:num; 
    for j = 1:num; 
     if dx(i,j)>0&&dy(i,j)>0; 
     kx(i,j) = (1/2)*(Dx-dx(i,j))*exp((-(Dx-dx(i,j))^2+(Dy-dy(i,j))^2)/4); 
     ky(i,j) = (1/2)*(Dy-dy(i,j))*exp((-(Dx-dx(i,j))^2+(Dy-dy(i,j))^2)/4); 
     end 
    end 
end 

sum_x = ones(1,num);% 1行N列0矩阵 
sum_y = ones(1,num); 

%fx = zeros(1,num); 


for i = 1:num; 
    for j = 1:num; 
     if dx(i,j)>0&&dy(i,j)>0; 
      fx(i) = p*kx(i,j);% j is neighbour to i 
      fy(i) = p*ky(i,j); 

      %fx(i) = matlabFunction(fx(i)); 
      %fy(i) = matlabFunction(fy(i)); 
      %P =quad2d(@(Dx,Dy) fx,0,0.01,0,0.01); 
      %fx =quad(@(Dx) fx,0,0.01); 
      %fx(i) =quad(@(Dy) fx(i),0,0.01); 
      %Q =quad2d(@(Dx,Dy) fy,0,0.01,0,0.01); 

      fx(i) = double(int(int(fx(i),Dx,0,0.01),Dy,0,0.01)); 
      fy(i) = double(int(int(fy(i),Dx,0,0.01),Dy,0,0.01)); 

      %fx(i) = vpa(p*kx(i,j)); 
      %fy(i) = vpa(p*ky(i,j)); 



      %fx(i) = dblquad(@(Dx,Dy)fx(i),0,0.01,0,0.01); 
      %fy(i) = dblquad(@(Dx,Dy)fy(i),0,0.01,0,0.01);   
      sum_x(i) = sum_x(i) + fx(i); 
      sum_y(i) = sum_y(i) + fy(i); 
     end 
    end 
end 

for i = 1:num; 
sum_x = 4.*sum_x./num; 
sum_y = 4.*sum_y./num; 
x(i) = x(i) - 0.05*sum_x(i); 
y(i) = y(i) - 0.05*sum_y(i); 
end 

a = a+1 

end 
hold on; 
scatter(x,y,'.','b') 

Answer 1

你的循环的快速版本应该是这样的：

qx = bsxfun(@minus, x_q.', x_q); 
qy = bsxfun(@minus, y_q.', y_q); 

il  = (qx.^2 + qy.^2 >= 0.01); 
qx(il) = 0; 
qy(il) = 0; 

il = qx>0 && qy>0; 
q = sum(exp(-((Dx-qx(il)).^2 + (Dy-qy(il)).^2)/4)); 

%// etc. for vectorization of the inner loops