Saving maximum values from last iteration.

Question

Daniel J 2024-3-30

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https://ww2.mathworks.cn/matlabcentral/answers/2100851-saving-maximum-values-from-last-iteration

评论： Daniel J 2024-3-31

Hi, I want to save maximum values from last iteration for every "ii". If i run code for a single "ii" it saves up the data properly, but when I run it in range from 1 to 10 it just saves the first one. What am I missing?

*Edited code as asked.

d = 2;
v=700;
om = 500;
dp=5;
dC=20;
m = 1;
S = pi * ((d^2) / 4);
r = 1.500;
g=8;
dt = 1e-5;
i = 1;
t(i) = 0;
t0 = 0;
max_values=zeros(10,3);
v0=zeros(1,10);
numb = [ 0 0 0 0;1 1 1 1; 2 2 2 2;3 3 3 3;4 4 4 4;5 5 5 5;6 6 6 6;7 7 7 7;8 8 8 8;9 9 9 9];
for ii = 1:10
    x(i)=numb(ii,1);
    y(i)=numb(ii,2);
    z(i)=numb(ii,3);
    v0(ii) = om * numb(ii,4) * 2 * pi;
    data = [0 0 300 240 180 120 60	0 330 300];
    if ii==1
        vz(i) = v;
        vy(i) = 0;
        vx(i) = 0;
    elseif ii>1 && ii<=7
        vz(i) = v;
        vy(i) = -v0(ii)*cosd(data(ii));
        vx(i) = v0(ii)*cosd(90-data(ii));
    elseif ii>7 && ii<=10
        vz(i) = v;
        vy(i) = -v0(ii)*cosd(data(ii));
        vx(i) = v0(ii)*cosd(90-data(ii));
    end
    while t < 500e-4
        dvz(i) = (-1/(2*m))*r*S*v*vz(i);
        dz(i) = vz(i);
        vz(i+1) = vz(i) + dvz(i) * dt;
        z(i+1) = z(i) + dz(i) * dt;
        dvy(i) = (-1/(2*m))*r*S*v*vy(i)-g;
        dy(i) = vy(i);
        vy(i+1) = vy(i) + dvy(i) * dt;
        y(i+1) = y(i) + dy(i) * dt;
        dvx(i) = (-1/(2*m))*r*S*v*vx(i);
        dx(i) = vx(i);
        vx(i+1) = vx(i) + dvx(i) * dt;
        x(i+1) = x(i) + dx(i) * dt;
        t(i+1) = t(i) + dt;
        i=i+1;
        max_values(ii,1)=max(x(i));
        max_values(ii,2)=max(y(i));
        max_values(ii,3)=max(z(i));
    end
end

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Manikanta Aditya 2024-3-30

在 MATLAB Online 中打开

@Alexander, I feel here the issue in within the scope of the variables, they are not being reset for each iteration of 'ii', which means the data from the previous iterations are being carried over into the next ones. This should be why only the results from the first iteration are seen.

Can initialise these variables inside the 'ii' loop:

d = 2;
v=700;
om = 500;
dp=5;
dC=20;
m = 1;
S = pi * ((d^2) / 4);
r = 1.500;
g=8;
dt = 1e-5;
max_values=zeros(10,3);
v0=zeros(1,10);
numb = [ 0 0 0 0;1 1 1 1; 2 2 2 2;3 3 3 3;4 4 4 4;5 5 5 5;6 6 6 6;7 7 7 7;8 8 8 8;9 9 9 9];
for ii = 1:10
    i = 1;
    t = zeros(1, 50000);
    t(i) = 0;
    x = zeros(1, 50000);
    y = zeros(1, 50000);
    z = zeros(1, 50000);
    vx = zeros(1, 50000);
    vy = zeros(1, 50000);
    vz = zeros(1, 50000);
    x(i)=numb(ii,1);
    y(i)=numb(ii,2);
    z(i)=numb(ii,3);
    v0(ii) = om * numb(ii,4) * 2 * pi;
    data = [0 0 300 240 180 120 60	0 330 300];
    if ii==1
        vz(i) = v;
        vy(i) = 0;
        vx(i) = 0;
    elseif ii>1 && ii<=7
        vz(i) = v;
        vy(i) = -v0(ii)*cosd(data(ii));
        vx(i) = v0(ii)*cosd(90-data(ii));
    elseif ii>7 && ii<=10
        vz(i) = v;
        vy(i) = -v0(ii)*cosd(data(ii));
        vx(i) = v0(ii)*cosd(90-data(ii));
    end
    while t(i) < 500e-4
        dvz(i) = (-1/(2*m))*r*S*v*vz(i);
        dz(i) = vz(i);
        vz(i+1) = vz(i) + dvz(i) * dt;
        z(i+1) = z(i) + dz(i) * dt;
        dvy(i) = (-1/(2*m))*r*S*v*vy(i)-g;
        dy(i) = vy(i);
        vy(i+1) = vy(i) + dvy(i) * dt;
        y(i+1) = y(i) + dy(i) * dt;
        dvx(i) = (-1/(2*m))*r*S*v*vx(i);
        dx(i) = vx(i);
        vx(i+1) = vx(i) + dvx(i) * dt;
        x(i+1) = x(i) + dx(i) * dt;
        t(i+1) = t(i) + dt;
        i=i+1;
        max_values(ii,1)=max(x);
        max_values(ii,2)=max(y);
        max_values(ii,3)=max(z);
    end
end

This way, for iternation of 'ii' it starts with fresh variables, and the results from the previous iterations won't affect the current one.

Alexander 2024-3-31

So I think you are pleased now.

Daniel J 2024-3-31

Sorry for late response, indeed now it works as inteded. Thank you so much and happy easter!

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Saving maximum values from last iteration.

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Saving maximum values from last iteration.

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