vector is not overwritten after certain interation during loop
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Hi guys,
I tried to write a small function to perform a random walk.
I've struggled with a strict vector formulation, so I created some mixture.
However, it works until the an certain interation loop, after that, the step directions (here stpx and stpy) are not overwritten whereas this is the case during the first interations.
The effect appears randomly between the 5th and 10th interation step.
Although k is changing, stpx and stpy are not.
"num" is my matrix with random numbers between 1 and 4
k in the loop takes for each iteration values from "num" and generates a new 5x1 vector for each interation
the idea was that stpx/stpy is computed each time again using the valid k-vector for the interation step.
function [x,y,num]=random_walk(n,x0,y0)
num=randi([1 4],5,n);
x(5,1)=x0;
y(5,1)=y0;
stpx(1)=-1;
stpx(2)=0;
stpx(3)=0;
stpx(4)=1;
stpy(1)=0;
stpy(2)=1;
stpy(3)=-1;
stpy(4)=0;
stpx_0=0;
stpy_0=0;
x(5,n+1)=0;
y(5,n+1)=0;
k0=0;
for a=1:n
k=k0+num(:,a);
stpx= stpx_0+[stpx(k(1,1));stpx(k(2,1));stpx(k(3,1));stpx(k(4,1));stpx(k(5,1))];
stpy= stpy_0+[stpy(k(1,1));stpy(k(2,1));stpy(k(3,1));stpy(k(4,1));stpy(k(5,1))];
x(:,a+1)=x(:,a)+stpx;
y(:,a+1)=y(:,a)+stpy;
end
end
Is this an issue because stpx and stpy have no indices?
Thank you all for the your help with this issue.
Kind regards, Dennis
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Dennis Trapp
2019-11-10
0 个投票
1 个评论
KALYAN ACHARJYA
2019-11-10
编辑：KALYAN ACHARJYA
2019-11-10
@Dennis
Glad to know that you resolved the issue. We're so happy you're here!
更多回答（1 个）
KALYAN ACHARJYA
2019-11-10
编辑：KALYAN ACHARJYA
2019-11-10
for a=1:n
k=k0+num(:,a);
stpx(a)= stpx_0+[stpx(k(1,1));stpx(k(2,1));stpx(k(3,1));stpx(k(4,1));stpx(k(5,1))];
stpy(a)= stpy_0+[stpy(k(1,1));stpy(k(2,1));stpy(k(3,1));stpy(k(4,1));stpy(k(5,1))];
x(:,a+1)=x(:,a)+stpx;
y(:,a+1)=y(:,a)+stpy;
end
Please note this iteration replace the stpx and stpy value ((Initializations)) until 1 to 4
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