Plotting a summation with two variables
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Hi All,
I need to plot a summation but I keep getting a blank plot,
Any help you can give would be great.
Here is my summation:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1347769/image.png)
Here is the code I have tried:
t = linspace(0,0.01,1);
x = linspace(0,0.01,1);
n = 100;
for k = 0:1:n
y = (6/(pi+6*k*pi))*sin(k*x)*exp((-(pi/6+k*pi)^2)*t);
end
plot(v,t)
Thanks
Alice
0 Comments
Accepted Answer
Torsten
on 6 Apr 2023
Edited: Torsten
on 6 Apr 2023
t = linspace(0,0.1,100);
x = linspace(0,1,100).';
n = 1000;
f = @(t) sum(6./(pi+6*(0:n)*pi).*sin(x.*(0:n)).*exp(-(pi/6+(0:n)*pi).^2*t),2);
for j = 1:numel(t)
F(:,j) = f(t(j));
end
figure(1)
plot(x,[F(:,1),F(:,10),F(:,15),F(:,20),F(:,100)])
figure(2)
plot(t,[F(1,:);F(10,:);F(15,:);F(20,:);F(100,:)])
10 Comments
Torsten
on 6 Apr 2023
Edited: Torsten
on 6 Apr 2023
You can use
t = linspace(0,0.1,100);
x = linspace(0,1,100).';
n = 1000;
f = @(t) sum(6./(pi+6*(0:n)*pi).*sin(x.*(0:n)).*exp(-(pi/6+(0:n)*pi).^2*t),2);
for j = 1:numel(t)
F(:,j) = f(t(j));
end
or
t = linspace(0,0.1,100);
x = linspace(0,1,100).';
n = 1000;
f = @(t) sum(6./(pi+6*(0:n)*pi).*sin(x.*(0:n)).*exp(-(pi/6+(0:n)*pi).^2*t),2);
F = cell2mat(arrayfun(@(t)f(t),t,'UniformOutput',0));
or
t = linspace(0,0.1,100);
x = linspace(0,1,100).';
n = 1000;
F = zeros(numel(x),numel(t));
for i = 1:numel(x)
xv = x(i);
for j = 1:numel(t)
tv = t(j);
for k = 0:n
F(i,j) = F(i,j) + 6/(pi+6*k*pi)*sin(xv*k)*exp(-(pi/6+k*pi)^2*tv);
end
end
end
F should be the same for all three codes, but I think for beginners, the last code is the easiest to understand.
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