plot a graph from loop

Question

Alina Abdikadyr 2023-2-17

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1914470-plot-a-graph-from-loop

评论： Star Strider 2023-2-17

在 MATLAB Online 中打开

Hello everyone!

Please, could you help me to plot the graphs using the loop

So, in my code I have the range of nv (nv=nmin:0.1:nmax)

for each value of nv, it plots the different parabolas. In figure 1, R vs V graph is plotted.

How to plot the graph of R vs V? (R depends on V by formula used in loop). I tried to implement nnew, but it gives me constan values.

So V is caluclated in loop. At the end, I have to get a graph of nv vs V (where V is changing parabolically with n).

At the end if i look at my genereted 10X45 matrix of c (which is the value of V) and 10X45 matrix of Rv (which is the value of Rv).

for each iteration i need to plot graphs in one figure. take the values of 2nd row of V and 2nd row of Rv

My code is:

clear all; close all
W = 10000;
S = 40;
AR=7;
cd0 = 0.005;
k = 1/pi/AR;
Psl=25000;
clalpha = 2*pi;
cdmin=4*cd0;
clmin=sqrt(3*cd0/k);
figure(1);hold on; xlabel('V');ylabel('P');
fun=@(n1) n1*W*(cdmin/clmin)*sqrt(2*n1*W/(1.225*S*clmin))-25000;
nmax = fzero(fun,2);
nmin=1/cos(0);
nv=nmin:0.1:nmax;
g=9.81;
%3.1
for k1 = 1:numel(nv)
    n = nv(k1);
    i=0;
    for alpha = 1:0.25:12
        i=i+1;
        cl(i) = clalpha * alpha * pi/180;
        V(i) = sqrt(2*n*W/1.225/S/cl(i));
        cd(i) = cd0 + k * cl(i) * cl(i);
        D(i) = n*W*cd(i)/cl(i);
        P(i) = D(i)*V(i);
        P_a(i)=Psl;
        R(i)=V(i)*V(i)/(g*sqrt(n*n-1));
        T(i)=2*pi*R(i)/V(i);
    end
    c(k1,:) = V; 
    Pm(k1,:) = P;                                                         
    Pma(k1,:) = P_a; 
    Rv(k1,:)=R;
    xix = find(diff(sign(D.*V-P_a)));                         
    if ~isempty(xix)                                                        
    for k3 = 1:numel(xix)
        idxrng = max(xix(k3)-1,1) : min(numel(V),xix(k3)+1);
        xv(k3) = interp1(P(idxrng)-P_a(idxrng), V(idxrng), 0);
        yv(k3) = interp1(V(idxrng),P(idxrng), xv(k3));
        Xm{k1,k3} = xv(k3);                                                 % Intersection X-Matrix
        Ym{k1,k3} = yv(k3);                                                 % Intersection Y-Matrix
    end
    end
   figure(1); plot(V,P)
   hold on 
   plot(V,P_a)
    plot(xv, yv, 's', 'DisplayName',sprintf('Intersections %d',k1))         % Plot Intersections (Optional)
    [minV,Vnidx] = min(V);
    Vstall(k1,:) = minV;
    Pstall(k1,:) = P(Vnidx);
    nvv(:,k1)=nv;
    [Pmin,idx] = min(P);
    minP(k1,:) = Pmin;
    Vm(k1,:) = V(idx);
    N=nvv(:,1);
    Vminp=Vm(:,1);
    figure(2); plot(c,Rv)
    figure(3); plot(V,T)
end
Table = cell2table(cat(2,Xm,Ym), 'VariableNames',{'V_p_max','V_p_min','Pmax','Pmin'});
Table = addvars(Table, Vstall, 'After','V_p_min');
Table = addvars(Table, N, 'Before','V_p_max');
Table = addvars(Table, Pstall, minP,Vminp,  'After','Pmin');

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Mathieu NOE 2023-2-17

hello

P is an array size 1 x 45

how do you wnt to plot P vs n which is a scalar

same reamark with nv wich size is 1 x 10

maybe you wanted one specific P value for each iteration ? like Pmin vs nv ?

Alina Abdikadyr 2023-2-17

sorry, i modified my question

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Answer 1

Sulaymon Eshkabilov 2023-2-17

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https://ww2.mathworks.cn/matlabcentral/answers/1914470-plot-a-graph-from-loop#answer_1174085

在 MATLAB Online 中打开

One of the possible ways to plot nv vs, V is to include cl values that leads to 3D plot, e.g.:

...
alpha = 1:0.25:12;
nv=nmin:0.1:nmax;
[ALF, NV]=meshgrid(alpha, nv);
CL = clalpha * ALF * pi/180;
Vall = sqrt(2*NV*W/1.225/S./CL);
surfc(ALF, CL, Vall)

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Alina Abdikadyr 2023-2-17

sorry, i edited my question

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Answer 2

Star Strider 2023-2-17

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1914470-plot-a-graph-from-loop#answer_1174145

在 MATLAB Online 中打开

Plotting ‘R’ as a function of ‘V’ is relatively straightforward:

figure

plot(V, R)

grid

xlabel('V')

ylabel('R')

What do you want to do with it afterwards?

clear all; close all

W = 10000;

S = 40;

AR=7;

cd0 = 0.005;

k = 1/pi/AR;

Psl=25000;

clalpha = 2*pi;

cdmin=4*cd0;

clmin=sqrt(3*cd0/k);

figure(1);hold on; xlabel('V');ylabel('P');

fun=@(n1) n1*W*(cdmin/clmin)*sqrt(2*n1*W/(1.225*S*clmin))-25000;

nmax = fzero(fun,2);

nmin=1/cos(0);

nv=nmin:0.1:nmax;

g=9.81;

%3.1

for k1 = 1:numel(nv)

n = nv(k1);

i=0;

for alpha = 1:0.25:12

i=i+1;

cl(i) = clalpha * alpha * pi/180;

V(i) = sqrt(2*n*W/1.225/S/cl(i));

cd(i) = cd0 + k * cl(i) * cl(i);

D(i) = n*W*cd(i)/cl(i);

P(i) = D(i)*V(i);

P_a(i)=Psl;

R(i)=V(i)*V(i)/(g*sqrt(n*n-1));

T(i)=2*pi*R(i)/V(i);

end

c(k1,:) = V;

Pm(k1,:) = P;

Pma(k1,:) = P_a;

Rv(k1,:)=R;

xix = find(diff(sign(D.*V-P_a)));

if ~isempty(xix)

for k3 = 1:numel(xix)

idxrng = max(xix(k3)-1,1) : min(numel(V),xix(k3)+1);

xv(k3) = interp1(P(idxrng)-P_a(idxrng), V(idxrng), 0);

yv(k3) = interp1(V(idxrng),P(idxrng), xv(k3));

Xm{k1,k3} = xv(k3); % Intersection X-Matrix

Ym{k1,k3} = yv(k3); % Intersection Y-Matrix

end

figure(1); plot(V,P)

hold on

plot(V,P_a)

plot(xv, yv, 's', 'DisplayName',sprintf('Intersections %d',k1)) % Plot Intersections (Optional)

[minV,Vnidx] = min(V);

Vstall(k1,:) = minV;

Pstall(k1,:) = P(Vnidx);

nvv(:,k1)=nv;

[Pmin,idx] = min(P);

minP(k1,:) = Pmin;

Vm(k1,:) = V(idx);

N=nvv(:,1);

Vminp=Vm(:,1);

figure(2); plot(c,Rv)

figure(3); plot(V,T)

end

figure

plot(V, R)

grid

xlabel('V')

ylabel('R')

figure

plot(V, R, 'LineWidth',2, 'DisplayName','R(V)')

hold on

plot(c,Rv, 'DisplayName','Rv(c)')

hold off

grid

xlabel('V')

ylabel('R')

% legend('Location','eastoutside')

Table = cell2table(cat(2,Xm,Ym), 'VariableNames',{'V_p_max','V_p_min','Pmax','Pmin'});

Table = addvars(Table, Vstall, 'After','V_p_min');

Table = addvars(Table, N, 'Before','V_p_max');

Table = addvars(Table, Pstall, minP,Vminp, 'After','Pmin');

.

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Alina Abdikadyr 2023-2-17

Thank you!

Could you please me to plot in one graph. I have a formula of R=V^2/(9.81*sqrt(n^2-1)) for a constant V I should plot R and n curve, and for constant n I should plot V n curve

Star Strider 2023-2-17

My pleasure!

I do not understand what you want to do. You plotted those together, however the ‘R’ here does not appear to be the same ‘R’ I plotted (and the only ‘R’ that I can find in your code).

What vectors are you plotting here, and where in your code are they calculated?

What constant values for ‘V’ and ‘n’ do you want to use?

Also, the ‘R’ and ‘n’ curves are not going to intersect when plotted on the same axes scales. What do you want to do with them?

My apologies, however I am confused here.

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