Plot generating blank graph?

Question

Zachary 2024-10-13

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2159305-plot-generating-blank-graph

评论： Image Analyst 2024-10-13

I have a code that stores values, calculates new values, then runs those calcuated variables through a for loop with two separate equations (Im1 and Im6), each with an unknown variable "t". However, when I ask MATLAB to plot the results of the loops, all I receive is a blank graph, as seen in the attachment. It is supposed to appear similar to the graph in the second attachment, with two lines for each of the equations. I don't know what is going wrong. I've added my current script below. Thank you.

l = 0.0001;
lambda = 0.405;
syms t;
wj11 = 0;
wj12 = -79.077;
wj61 = 0;
wj62 = -0.014533;
wj63 = -0.0682;
wj64 = -0.1947;
wj65 = -1.023;
wj66 = -2.896;
wj67 = -79.4;
Bj11 = 0.00097;
Bj12 = 0.99903;
Bj61 = Bj11;
Bj62 = 0.000091;
Bj63 = 0.000664;
Bj64 = 0.000901;
Bj65 = 0.001282;
Bj66 = 0.001292;
Bj67 = 0.9948;
Beta1m1 = (Bj11*lambda)/((wj11+lambda)^2);
Beta2m1 = (Bj12*lambda)/((wj12+lambda)^2);
Beta1m6 = (Bj61*lambda)/((wj61+lambda)^2);
Beta2m6 = (Bj62*lambda)/((wj62+lambda)^2);
Beta3m6 = (Bj63*lambda)/((wj63+lambda)^2);
Beta4m6 = (Bj64*lambda)/((wj64+lambda)^2);
Beta5m6 = (Bj65*lambda)/((wj65+lambda)^2);
Beta6m6 = (Bj66*lambda)/((wj66+lambda)^2);
LB1 = Beta1m6;
LB2 = LB1+Beta2m6;
LB3 = LB2+Beta3m6;
LB4 = LB3+Beta4m6;
LB5 = LB4+Beta5m6;
LB6 = LB5+Beta6m6;
for t=0:0.1:1
    Im1 = (exp(wj11*t)/(l+Beta1m1))+(exp(wj12*t)/(l+Beta2m1));
    I1m6 = (exp(wj61*t)/LB1);
    I2m6 = (exp(wj62*t)/LB2);
    I3m6 = (exp(wj63*t)/LB3);
    I4m6 = (exp(wj64*t)/LB4);
    I5m6 = (exp(wj65*t)/LB5);
    I6m6 = (exp(wj66*t)/LB6);
    Im6 = I1m6+I2m6+I3m6+I4m6+I5m6+I6m6;
end 
disp(Im1)
disp(Im6)
plot(Im1,'LineWidth',2);
hold on
plot(Im6,'Linewidth',2)

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Chuguang Pan 2024-10-13

The values of Im1 and Im6 in your for loop are reassigned repeatly, so that you get the scalar in the last loop. The plot function can not plot a standalone scalar value.

Zachary 2024-10-13

I'm sorry, I'm confused. Why can't MATLAB take simplified values (with one variable) and plot them between a range?

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Answer 1

Image Analyst 2024-10-13

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2159305-plot-generating-blank-graph#answer_1531565

在 MATLAB Online 中打开

You need to index Im1 and Im6. Otherwise you're just overwriting a single number in your loop and not creating a vector of several values that can be plotted as a function of t. See corrected code below. Adapt as needed.

% Demo by Image Analyst.

% Initialization steps.

clc; % Clear the command window.

fprintf('Beginning to run %s.m ...\n', mfilename);

Beginning to run LiveEditorEvaluationHelperEeditorId.m ...

close all; % Close all figures (except those of imtool.)

clearvars;

workspace; % Make sure the workspace panel is showing.

format long g;

format compact;

fontSize = 16;

lineWidth = 2;

markerSize = 30;

l = 0.0001;

lambda = 0.405;

% syms tIndex;

wj11 = 0;

wj12 = -79.077;

wj61 = 0;

wj62 = -0.014533;

wj63 = -0.0682;

wj64 = -0.1947;

wj65 = -1.023;

wj66 = -2.896;

wj67 = -79.4;

Bj11 = 0.00097;

Bj12 = 0.99903;

Bj61 = Bj11;

Bj62 = 0.000091;

Bj63 = 0.000664;

Bj64 = 0.000901;

Bj65 = 0.001282;

Bj66 = 0.001292;

Bj67 = 0.9948;

Beta1m1 = (Bj11*lambda)/((wj11+lambda)^2);

Beta2m1 = (Bj12*lambda)/((wj12+lambda)^2);

Beta1m6 = (Bj61*lambda)/((wj61+lambda)^2);

Beta2m6 = (Bj62*lambda)/((wj62+lambda)^2);

Beta3m6 = (Bj63*lambda)/((wj63+lambda)^2);

Beta4m6 = (Bj64*lambda)/((wj64+lambda)^2);

Beta5m6 = (Bj65*lambda)/((wj65+lambda)^2);

Beta6m6 = (Bj66*lambda)/((wj66+lambda)^2);

LB1 = Beta1m6;

LB2 = LB1+Beta2m6;

LB3 = LB2+Beta3m6;

LB4 = LB3+Beta4m6;

LB5 = LB4+Beta5m6;

LB6 = LB5+Beta6m6;

t = 0:0.1:1

t = 1×11

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

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

for tIndex = 1 : numel(t)

this_t = t(tIndex); % Get this particular value of t from the vector of t values.

% Assign this particular value of Im1. Need to give it the index so it

% goes into the proper location of the vector.

Im1(tIndex) = (exp(wj11*this_t)/(l+Beta1m1))+(exp(wj12*this_t)/(l+Beta2m1));

I1m6 = (exp(wj61*this_t)/LB1);

I2m6 = (exp(wj62*this_t)/LB2);

I3m6 = (exp(wj63*this_t)/LB3);

I4m6 = (exp(wj64*this_t)/LB4);

I5m6 = (exp(wj65*this_t)/LB5);

I6m6 = (exp(wj66*this_t)/LB6);

% Assign this particular value of Im6. Need to give it the index so it

% goes into the proper location of the vector.

Im6(tIndex) = I1m6+I2m6+I3m6+I4m6+I5m6+I6m6;

end

disp(Im1)

Columns 1 through 6 6447.75687139828 403.016364430728 400.792505741751 400.791687584634 400.791687283634 400.791687283523 Columns 7 through 11 400.791687283523 400.791687283523 400.791687283523 400.791687283523 400.791687283523

disp(Im6)

Columns 1 through 6 1208.32551171607 1181.20888523427 1159.07727742499 1140.78598141995 1125.46827162041 1112.46645460124 Columns 7 through 11 1101.2801646105 1091.52757665354 1082.91629725429 1075.22150683602 1068.26953695826

plot(t, Im1, 'r.-', 'LineWidth', lineWidth, 'MarkerSize', markerSize);

hold on

plot(t, Im6, 'b.-', 'LineWidth', lineWidth, 'MarkerSize', markerSize)

grid on;

xlabel('t', 'FontSize', fontSize);

ylabel('Value of Im1 or Im6', 'FontSize', fontSize);

legend('Im1', 'Im6');

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Image Analyst 2024-10-13

Or, the more MATLABy way of doing it, you can do it vectorized like Star showed you. That's actually how most of us would do it. I just showed you the for loop way because that's how you started it.

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Answer 2

Star Strider 2024-10-13

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2159305-plot-generating-blank-graph#answer_1531445

在 MATLAB Online 中打开

You do not need the loop.

Just usee vectorisation —

l = 0.0001;

lambda = 0.405;

syms t;

wj11 = 0;

wj12 = -79.077;

wj61 = 0;

wj62 = -0.014533;

wj63 = -0.0682;

wj64 = -0.1947;

wj65 = -1.023;

wj66 = -2.896;

wj67 = -79.4;

Bj11 = 0.00097;

Bj12 = 0.99903;

Bj61 = Bj11;

Bj62 = 0.000091;

Bj63 = 0.000664;

Bj64 = 0.000901;

Bj65 = 0.001282;

Bj66 = 0.001292;

Bj67 = 0.9948;

Beta1m1 = (Bj11*lambda)/((wj11+lambda)^2);

Beta2m1 = (Bj12*lambda)/((wj12+lambda)^2);

Beta1m6 = (Bj61*lambda)/((wj61+lambda)^2);

Beta2m6 = (Bj62*lambda)/((wj62+lambda)^2);

Beta3m6 = (Bj63*lambda)/((wj63+lambda)^2);

Beta4m6 = (Bj64*lambda)/((wj64+lambda)^2);

Beta5m6 = (Bj65*lambda)/((wj65+lambda)^2);

Beta6m6 = (Bj66*lambda)/((wj66+lambda)^2);

LB1 = Beta1m6;

LB2 = LB1+Beta2m6;

LB3 = LB2+Beta3m6;

LB4 = LB3+Beta4m6;

LB5 = LB4+Beta5m6;

LB6 = LB5+Beta6m6;

% for t=0:0.1:1

t=0:0.1:1;

Im1 = (exp(wj11*t)/(l+Beta1m1))+(exp(wj12*t)/(l+Beta2m1));

I1m6 = (exp(wj61*t)/LB1);

I2m6 = (exp(wj62*t)/LB2);

I3m6 = (exp(wj63*t)/LB3);

I4m6 = (exp(wj64*t)/LB4);

I5m6 = (exp(wj65*t)/LB5);

I6m6 = (exp(wj66*t)/LB6);

Im6 = I1m6+I2m6+I3m6+I4m6+I5m6+I6m6;

% end

disp(Im1)

1.0e+03 * 6.4478 0.4030 0.4008 0.4008 0.4008 0.4008 0.4008 0.4008 0.4008 0.4008 0.4008

disp(Im6)

1.0e+03 * 1.2083 1.1812 1.1591 1.1408 1.1255 1.1125 1.1013 1.0915 1.0829 1.0752 1.0683

plot(Im1,'LineWidth',2);

hold on

plot(Im6,'Linewidth',2)

.

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