Why are the lines not showing up on my graph?

I need to show two separate lines on the same figure, one for dcs and one for d2p, using the values provided by each iteration of the for loop. I'm not sure what I'm doing wrong here. Thanks in advance! Here is my code:

N = [10 90 1000]; % number of peers
F = 20 * 1024; % converting Gbits to Mbits
us = 30; % server upload
di = 2; % client download
u = 300/1024; % client upload

dcs = zeros(size(N));
dp2 = zeros(size(N));

figure();
grid
hold on;

for i = 1:1:length(N)
    Nval = N(i);

    cs1 = Nval*F/us;
    cs2 = F/di;
    dcs = max(cs1,cs2);

    p21 = F/us;
    ui = u*Nval;
    p23 = Nval*F/(us+ui);
    dp2 = max([p21(:); cs2(:); p23(:)]);
    
    plot(dcs, Nval);
    plot(dp2, Nval);
    title('Distribution Time')
end

ylabel('Minimum Distribution Time')
xlabel('N')

[Carine]

why does lines on my graph does not show? It gives me an empty plot. Here is my code

clear;
x0 = 1; eps = 0.000001; p = 425; f = @(x) p*((3^.5)*sind(x)+p*cosd(x))-800;fd = @(x) (3^.5)*p*cosd(x)-p*sind(x); f0 = f(x0); fd0 = fd(x0);
for i = p:25:800
    q = p*sind(x0)/sind(30);
    fprintf('%4d     %8.3f       %8.3f       %8.3f       %8.3f\n', i, x0, f0, fd0, q)
    x = x0 - f0/fd0; f0 = f(x); fd0 = fd(x);
    if abs(x-x0) < eps; break;
    end
    x0 = x; q = p*sind(x)/sind(30);
end

 425        1.000       179810.337        728.592         14.835
 450     -245.791       -74195.506       -689.478        775.250
 475     -353.403       178713.453        682.417         97.659
 500     -615.285       -45967.358       -598.039        822.123
 525     -692.149       159246.266        452.304        397.098
 550     -1044.227       146178.039        348.797        496.892
 575     -1463.319       164778.858        844.228       -336.477
 600     -1658.502       -141696.181       -840.659        529.162
 625     -1827.056       159723.226        848.878       -386.630
 650     -2015.214       -147947.110       -846.483        490.136
 675     -2189.992       155269.748        850.000       -424.903
 700     -2372.663       -152464.011       -849.082        458.739
 725     -2552.226       151607.313        849.359       -453.272
 750     -2730.722       -155698.847       -849.932        434.246
 775     -2913.912       148689.225        848.020       -474.231
 800     -3089.249       -158036.465       -849.927        415.315

plot(fd0, i), grid on, xlabel('Theta (degrees)'), ylabel('P & Q (N)'), hold on; plot(x, q), legend('P', 'Q'), title('Variation of P and Q with respect to θ')

[Voss]

Check the values you are plotting (fd0 and i). They are both scalars. Plotting a scalar vs a scalar is plotting a single point. A single point will not render without a data marker.

clear;
x0 = 1; eps = 0.000001; p = 425; f = @(x) p*((3^.5)*sind(x)+p*cosd(x))-800;fd = @(x) (3^.5)*p*cosd(x)-p*sind(x); f0 = f(x0); fd0 = fd(x0);
for i = p:25:800
    q = p*sind(x0)/sind(30);
    fprintf('%4d     %8.3f       %8.3f       %8.3f       %8.3f\n', i, x0, f0, fd0, q)
    x = x0 - f0/fd0; f0 = f(x); fd0 = fd(x);
    if abs(x-x0) < eps; break;
    end
    x0 = x;% q = p*sind(x)/sind(30);
end

 425        1.000       179810.337        728.592         14.835
 450     -245.791       -74195.506       -689.478        775.250
 475     -353.403       178713.453        682.417         97.659
 500     -615.285       -45967.358       -598.039        822.123
 525     -692.149       159246.266        452.304        397.098
 550     -1044.227       146178.039        348.797        496.892
 575     -1463.319       164778.858        844.228       -336.477
 600     -1658.502       -141696.181       -840.659        529.162
 625     -1827.056       159723.226        848.878       -386.630
 650     -2015.214       -147947.110       -846.483        490.136
 675     -2189.992       155269.748        850.000       -424.903
 700     -2372.663       -152464.011       -849.082        458.739
 725     -2552.226       151607.313        849.359       -453.272
 750     -2730.722       -155698.847       -849.932        434.246
 775     -2913.912       148689.225        848.020       -474.231
 800     -3089.249       -158036.465       -849.927        415.315

Both scalars:

fd0

fd0 = 846.5149

i

i = 800

Here's a plot of i vs fd0 using a data marker ('s' for 'square'); the plotted point is on the top edge of the axes, above the legend.

plot(fd0, i, '-s'), grid on, xlabel('Theta (degrees)'), ylabel('P & Q (N)'), hold on; plot(x, q), legend('P', 'Q'), title('Variation of P and Q with respect to θ')

[Carine]

what should i change on that code to make it a non-scalar?

[Voss]

If you want to store the fd0 value from each iteration, something like this:

clear;
x0 = 1; eps = 0.000001; p = 425; f = @(x) p*((3^.5)*sind(x)+p*cosd(x))-800; fd = @(x) (3^.5)*p*cosd(x)-p*sind(x); f0 = f(x0); fd0 = fd(x0);
i_all = p:25:800;
N = numel(i_all);
fd0_all = NaN(1,N);
for ii = 1:N
    fd0_all(ii) = fd0;
    q = p*sind(x0)/sind(30);
    fprintf('%4d     %8.3f       %8.3f       %8.3f       %8.3f\n', i_all(ii), x0, f0, fd0, q)
    x = x0 - f0/fd0; f0 = f(x); fd0 = fd(x);
    if abs(x-x0) < eps; break;
    end
    x0 = x;% q = p*sind(x)/sind(30);
end

 425        1.000       179810.337        728.592         14.835
 450     -245.791       -74195.506       -689.478        775.250
 475     -353.403       178713.453        682.417         97.659
 500     -615.285       -45967.358       -598.039        822.123
 525     -692.149       159246.266        452.304        397.098
 550     -1044.227       146178.039        348.797        496.892
 575     -1463.319       164778.858        844.228       -336.477
 600     -1658.502       -141696.181       -840.659        529.162
 625     -1827.056       159723.226        848.878       -386.630
 650     -2015.214       -147947.110       -846.483        490.136
 675     -2189.992       155269.748        850.000       -424.903
 700     -2372.663       -152464.011       -849.082        458.739
 725     -2552.226       151607.313        849.359       -453.272
 750     -2730.722       -155698.847       -849.932        434.246
 775     -2913.912       148689.225        848.020       -474.231
 800     -3089.249       -158036.465       -849.927        415.315

i_all

i_all = 1×16

425 450 475 500 525 550 575 600 625 650 675 700 725 750 775 800

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fd0_all

fd0_all = 1×16

728.5922 -689.4783 682.4174 -598.0387 452.3042 348.7965 844.2285 -840.6588 848.8781 -846.4831 850.0000 -849.0822 849.3586 -849.9325 848.0195 -849.9270

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

plot(fd0_all, i_all, '-s'), grid on, xlabel('Theta (degrees)'), ylabel('P & Q (N)'), hold on; plot(x, q), legend('P', 'Q'), title('Variation of P and Q with respect to θ')

Answer 1

[Star Strider]

I am not certain what you want to do.

Try this:

N = [10 90 1000]; % number of peers
F = 20 * 1024; % converting Gbits to Mbits
us = 30; % server upload
di = 2; % client download
u = 300/1024; % client upload

dcs = zeros(size(N));
dp2 = zeros(size(N));

figure();
grid
hold on;

for i = 1:1:length(N)
    Nval = N(i);

    cs1 = Nval*F/us;
    cs2 = F/di;
    dcs(i) = max(cs1,cs2);

    p21 = F/us;
    ui = u*Nval;
    p23 = Nval*F/(us+ui);
    dp2(i) = max([p21(:); cs2(:); p23(:)]);

end

figure();
grid
hold on;
    plot(dcs, N, '-p');
    plot(dp2, N, '-p');
    title('Distribution Time')
ylabel('Minimum Distribution Time')
xlabel('N')

or perhaps instead:

    plot(N, dcs, '-p');
    plot(N, dp2, '-p');

Otherwise, note that you are plotting points, not lines, so you need to plot markers in the loop.

[Bailey Eaton]

This worked! Thank you!

[Star Strider]

As always, my pleasure!

Answer 2

[Walter Roberson]

N = [10 90 1000]; % number of peers
F = 20 * 1024; % converting Gbits to Mbits
us = 30; % server upload
di = 2; % client download
u = 300/1024; % client upload

dcs = zeros(size(N));
dp2 = zeros(size(N));

figure();
grid
hold on;

for i = 1:1:length(N)
    Nval = N(i);

    cs1 = Nval*F/us;
    cs2 = F/di;
    dcs = max(cs1,cs2);

    p21 = F/us;
    ui = u*Nval;
    p23 = Nval*F/(us+ui);
    dp2 = max([p21(:); cs2(:); p23(:)]);
    
    plot(dcs, Nval, 'k*-');
    plot(dp2, Nval, 'b+-');
    title('Distribution Time')
end

ylabel('Minimum Distribution Time')
xlabel('N')

MATLAB only connects points with a line when you plot() or line() in a situation where you have a minimum of two consecutive finite values in a single call. Your dcs and dps2 are scalar and your Nval are as well, so you are never plotting at least two consecutive points in a single call. You should consider storing all of the values in vectors and plotting them after the loop is done.

Also, your code implies that N is the number of peers, which would appear to be the independent variable, and dcs and dps2 would appear to be dependent variables. As such, convention would be that independent variable N should appear on the X axis (like you labeled) and the dependent variable should appear on the Y axis (like you labeled.) But that is not what you plotted: your plot() statements have your dependent variable along the x axis and your independent variable along the y axes.