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problem in running time of my project

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f4r3in
f4r3in 2019 年 11 月 6 日
コメント済み: f4r3in 2019 年 11 月 8 日
hi, my project running time make me crazy.
I write a script with only 3 " for " but when I click on run button it takes 166 second to run that.
I try it in other computers and Ihave same problem so I realize that the problem is in my script.
with same inputs my friend write another script and we both get same output but his script ran in 3 seconds and my script runs in 166 seconds. (why?) (we have same laptops)
my laptop's specs :
cpu = corei7 5500U
ram = 8 GB
here is my code please tell me where is the problem that I cant get answer in few seconds.
clc
clear
tic;
Input = [ 5 12 0.02
4 20 0.1
6 50 0.01
4 76 0.02
3 100 0.04
4 155 0.04
3 197 0.05
1 350 0.08
2 400 0.12];
n=Input(:,1);
cap=Input(:,2);
FOR=Input(:,3);
COPT=zeros;
copt1=zeros;
Prob=zeros;
%copt 1
for i=0:n(1)
copt1(i+1,1) = cap(1)*i;
copt1(i+1,2) = (nchoosek(n(1),i))*(FOR(1)^(i))*((1-FOR(1))^(n(1)-i));
end
l=1;
for i=1:size(copt1,1)
COPT(l,1)=copt1(i,1);
COPT(l,2)=copt1(i,2);
l=l+1;
end
%problem is starts from here
for i=2:size(cap,1)
a=size(COPT,1);
for j=1:n(i)
for k=1:a
COPT(l,1)=cap(i)*j + COPT(k,1);
l=l+1;
end
end
end
toc;
  2 件のコメント
f4r3in
f4r3in 2019 年 11 月 7 日
Yes the output must be an array with 504000*2 dimensions and we both get same output. but you said it is because of "l" and that "l" must be there it fills the rows of COPT and after one row filled the next row filled by "l"

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Shubham Gupta
Shubham Gupta 2019 年 11 月 7 日
編集済み: Shubham Gupta 2019 年 11 月 7 日
I changed one simple thing, it was working more efficiently for me:
clc
clear;
tic;
Input = [ 5 12 0.02
4 20 0.1
6 50 0.01
4 76 0.02
3 100 0.04
4 155 0.04
3 197 0.05
1 350 0.08
2 400 0.12];
n=Input(:,1);
cap=Input(:,2);
FOR=Input(:,3);
COPT=zeros;
copt1=zeros;
Prob=zeros;
%copt 1
for i=0:n(1)
copt1(i+1,1) = cap(1)*i;
copt1(i+1,2) = (nchoosek(n(1),i))*(FOR(1)^(i))*((1-FOR(1))^(n(1)-i));
end
COPT =copt1(:,1); % I removed second loop and in place made COPT a column vector
l=size(COPT,1)+1;
for i=2:size(cap,1)
a=size(COPT,1);
for j=1:n(i)
for k=1:a
COPT(l,1)=cap(i)*j + COPT(k,1);
l=l+1;
end
end
end
COPT(:,2) = zeros(size(COPT,2));
COPT(1:6,2) = copt1(:,2);
toc;
I believe this is something to do with not prelocating the size of an array, MATLAB uses more memory and bigger the dimesion of the matrix more is the time taken to change the size of it. Let me know if this works for you .
  3 件のコメント
f4r3in
f4r3in 2019 年 11 月 8 日

Thanks a lot

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