I am running this code 100 times, generating multiple random numbers and using those random numbers to determine if a particle has leaked left(NL) leaked right(NL) abdorbed(NA). If scattering happens, then I want the code to return to recalculate mu.

%Prob2,Case 1

clc;

clear all;

tic

sigmatot=1;

sigmascat=0.5;

L=1;

x1=0.1;

x2=0.3;

N=100;

NL=0;

NR=0;

NA=0;

for i=1:N

k=0;

x=x1+(x2-x1)*rand()

k=1;%I want to re-start here if eta>c

mu=2*rand()-1;

deltax=-(mu/sigmatot)*(log(rand()));

r=x+deltax

if r<0

NL=NL+1;

end

if r>L

NR=NR+1;

else

c=sigmascat/sigmatot;

eta=rand();

if eta <= c

k=1;

end

if eta > c

NA=NA+1;

end

while k==1

%At this point, if eta>c I want the code to restart calculating

%mu

end

end

end

[Shubham Khatri]

Hello,

Can you please elaborate on exactly what issue you are facing?

Thanks

Answer 1

[Sanju]

Hi @ chan chang,

To restart the calculation of ‘mu‘ whenever scattering occurs , your code can be updated as follows,

while k == 1
            mu = 2 * rand() - 1; % recalculating mu
            deltax = -(mu / sigmatot) * (log(rand()));% recalculating deltax
            r = x + deltax;% recalculating r

            if r < 0
                NL = NL + 1;
                k = 0; % Exit the while loop
            end

            if r > L
                NR = NR + 1;
                k = 0; % Exit the while loop
            else
                eta = rand();

                if eta <= c 
                    k = 1;
                end

                if eta > c
                    NA = NA + 1; 
                    k = 0; % Exit the while loop
                end
            end
        end

This code runs a simulation 100 times, tracking particles and their interactions with a medium. If a particle scatters, the code recalculates the scattering angle and resumes the simulation from the scattering point.

You can also refer to the below documentation links if required,

https://www.mathworks.com/help/matlab/ref/rand.html

https://www.mathworks.com/help/matlab/ref/log.html

Hope this Helps!