Plotting summation function in loop

Plotting summation function in loop

[KL]

Did you try anything yet?

[Yuhang Ma]

Yes, I did. Tried to use loop, but it doesn't work. Here are my code

lnR = 0.2*rand(1,500);
X = exp(lnR)-1.1;
g = 0;
for i = 1:100

    g = g + X(i)/(1+a*X(i))
    fplot(g,[0:100:5])
end

[Jan]

@Yuhang Ma: Whenever you write "does not work" in a forum, add the details. It is much easier to solve a problem than to guess, what the problem is.

[Yuhang Ma]

Sorry, this is my first time asking question in a forum. Let finish my question. My code is as follow. I was trying to use for loop the alpha to find value g in function f and plot the graph. However the figure shows no line.

lnR = 0.2*rand(1,500);
X = exp(lnR)-1.1;
a = linspace(0,5,100);
f = @(a) sum(X./(1+a.*X));
for i = 1:length(a)
  g = f(a(i));  
end
plot(a,g)

Answer 1

[KL]

Alright, you have defined lnR and X correctly,

lnR = 0.2*rand(1,500);
X = exp(lnR)-1.1;

Then they have asked you to define an inline function, I'd recommend to read this link: https://de.mathworks.com/help/matlab/matlab_prog/anonymous-functions.html

For your case,

 func = @(alpha) sum(X./(1+alpha.*X));

Now you have to define alpha in the interval 0 to 5 with 100 mesh points,

 hint: alpha=linspace(from,to,no_of_points)

then you have to pass alpha to func to calculate g, you will get one value of g for every alpha, so finally you will have 100 g, which you can plot using,

 plot(g)

[KL]

replace

 g = f(a(i));

with

 g(i) = f(a(i));

this way you store results from every iteration in an array, previously you had been overwriting.

[Yuhang Ma]

Thank you so much!