how to use array indices in not logical form

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arash rad 2022-7-25

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https://ww2.mathworks.cn/matlabcentral/answers/1767105-how-to-use-array-indices-in-not-logical-form

评论： Walter Roberson 2022-7-25

Hi

I am working on a project and I have the equation below and when I use for loops because my T is a float Number something like 0.15 I get an error that I should use positive or logical numbers how sholud I fix that ??

thank you

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arash rad 2022-7-25

编辑：Matt J 2022-7-25

在 MATLAB Online 中打开

%-- Extract some data
arrival=xlsread('tripinfo.xlsx','G:G');
depart_time=xlsread('tripinfo.xlsx','B:B');
speed_m = xlsread('loop.xlsx','G:G');
N_veh = xlsread('loop.xlsx','J:J');
Nt = length(speed_m)/2;
speed = zeros(Nt,1);
vehicle_number = zeros(Nt,1);
qu = zeros(Nt,1);
%-- Here we calculate number of vehicles that we need for calcualtion
%parameters
for k = 1:Nt;
    
    speed(k,1) = [speed_m((2*k)-1) + speed_m(2*k)]/2;
    vehicle_number(k,1) = [N_veh((2*k)-1) + N_veh(2*k)];
    qu(k,:) = vehicle_number(k,1);
    
    
    
end
speed;  
vehicle_number;
qu = qu';
%-- first we want to extract data from sumo in every 10 minutes.in step one
%we want to calculate how many cars are in the intersection in specific
%intersection
figure;
bar(qu)
title("Upstream Flow")
%% calculate parametrs
delta_x = 500 - 70 ;
T = zeros(Nt,1);
for i =1:length(qu)
    tm(i,:) = ((1/qu(i))*(delta_x/speed(i)));
    T(i) = delta_x/(speed(i)); %lag time 
end
tm ;
beta = 0.8;
alpha = 0.5;
ta = beta*tm; %lag time 
Ftu_den = 1+(alpha*ta);
Ftu = 1./Ftu_den;
%% Arriving flow distribution
qd = zeros(Nt,1);
for j =ta:ta+length(qu))
    qd(:,j) = ((((1-Ftu).^(j-ta(j)))).*Ftu)*qu(j)
end 

Walter Roberson 2022-7-25

在 MATLAB Online 中打开

tm(i,:) = ((1/qu(i))*(delta_x/speed(i)));

tm is a vector or perhaps a 2D array. Not scalar.

beta = 0.8;
alpha = 0.5;
ta = beta*tm; %lag time 

ta is a constant multiple times tm, and tm is non-scalar so ta is non-scalar.

for j =ta:ta+length(qu))

What does it mean to have a for loop whose lower bound is an array ?

qd(:,j) = ((((1-Ftu).^(j-ta(j)))).*Ftu)*qu(j)

Suppose the for loop somehow managed to assign the full array ta to j . Then you use ta(j) so you would be indexing ta at the values of ta . Are you sure that is wise?

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