Plotting trendline and normally distributed numbers

Hello guys,

I would need some help wtih the following problem.

I need to plot the calculated numbers (Nkonstant, Ntrend, Nsaisonal, NtrendSaisonal) as shown in my code.

So far i works out as I intended it to.

• But now i need to add the trendlines to the plots (I already calculated them in the for loop)
• and I need to change my variable e in a way that it represents normally distributed numbers with a mean 0 and a standard deviation of 20.

Would be so great if someone has got a solution to this.

Best regards,

Alex

clc; 
close all; 
clear all; 
rng('default'); 

m = 100; 
k = 1.2; 
A = 50; 
T = 13; 


for t = 1:1:52; 
    
    e = randn();
    
    Nkonstant = m + e;
    Ntrend = m + k *t + e;
    Nsaisonal = m + A*sin((2*t*pi)/T) + e;
    NtrendSaisonal = m + k*t + A*sin((2*t*pi)/T) + e;
    
    trendline1 = m; 
    trendline2 = m + k*t; 
    trendline3 = m + A*sin((2*t*pi)/T); 
    trendline4 = m + k*t + A*sin((2*t*pi)/T); 

   
    subplot(2,2,1);
    plot(t, Nkonstant,'o');
    hold on; 
    
    subplot(2,2,2);
    plot(t, Ntrend,'o');
    hold on; 
    
    subplot(2,2,3);
    plot(t, Nsaisonal,'o');
    hold on; 
    
    subplot(2,2,4);
    plot(t, NtrendSaisonal,'o');
    hold on; 
    
end

Answer 1

[Adam Danz]

"I need to change my variable e in a way that it represents normally distributed numbers with a mean 0 and a standard deviation of 20. "

randn returns random number from a standard normal distribution with mean 0 and standard deviation or 1. To get a std of 20, just multiply by 20. Here's a demo

n = randn(1,100000) * 20; 
std(n)
% ans =
%        20.015   % your value may differ slightly

" i need to add the trendlines to the plots (I already calculated them in the for loop)"

See refline.

[Alexander Tollinger]

yeah unfortunately the trendline stil does not work. Can't figure it out

[Adam Danz]

Share what you have tried. What are the values of your trendline coefficients and what function are you using to plot them?