Linear Regression (polyfit) how to show equation and find R?

Hi there,

Nothing I try seems to work. I have a graph with a linear regression line. I want to know the equation of the line (y=mx+b) and the error R value. Here is my code:

clc

clear all

ActE=[1.672 2.573 2.696 3.300 3.835 4.489]*1e-19;
Freq=[3.60 4.77 5.03 5.72 6.60 7.51]*1e14;
c=polyfit(Freq,ActE,1);
ActE_est=polyval(c,Freq);
plot(Freq,ActE,'*');
grid
title('Frequency vs Activation Energy');
xlabel('Frequency (Hz)');
ylabel('Activation Energy (J)');
hold on
plot(Freq,ActE_est);
legend('Data','Fitted Curve','Location','northwest');

Answer 1

[Subhadeep Koley]

Use the code below to find the line equation and fit error (R). This code saves Frequency, Activation Energy, Fit, and Fit Error (R) inside the table T.

warning off; close all;clc;
ActE=[1.672 2.573 2.696 3.300 3.835 4.489]*1e-19;
Freq=[3.60 4.77 5.03 5.72 6.60 7.51]*1e14;
c=polyfit(Freq,ActE,1); % Here 'c' contains the 'm' and 'b'
ActE_est=polyval(c,Freq);
plot(Freq,ActE,'*');
grid
title(['Line Equation is y = ',num2str(c(1)),'*x + ','(',num2str(c(2)),')']);
xlabel('Frequency (Hz)');
ylabel('Activation Energy (J)');
hold on
plot(Freq,ActE_est);
legend('Data','Fitted Curve','Location','northwest');
disp(['Line Equation is y = F(x) = ',num2str(c(1)),'*x + ','(',num2str(c(2)),')']);
% Fit error (R) = ActE-ActE_est
T = table(Freq',ActE',ActE_est',(ActE-ActE_est)','VariableNames',{'Frequency','Activation_Energy','Fit','Fit_Error_R'})

Hope this helps!