# Plotting trendline and normally distributed numbers

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Alexander Tollinger on 29 Mar 2020
Edited: Adam Danz on 31 Mar 2020
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

Adam Danz on 29 Mar 2020
"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 on 29 Mar 2020
yeah unfortunately the trendline stil does not work. Can't figure it out
Adam Danz on 29 Mar 2020
Edited: Adam Danz on 31 Mar 2020
Share what you have tried. What are the values of your trendline coefficients and what function are you using to plot them?

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