MATLAB: How to make the line of best fit go through the origin

Question

Effectivenormalstress=[41,79,119,159,197,80];

Maximumshearstress=[34,73,97,138,173,56];

x=Effectivenormalstress;

y=Maximumshearstress;

scatter(x, y, 'rx');

xlabel('Effective normal stress');

ylabel('Shear stress');

sgtitle('Interpretation for angles of shearing resistance');

coefficients=polyfit(x, y, 1);

xFit=linspace(min(x),max(x),1000);

yFit=polyval(coefficients, xFit);

hold on;

plot(xFit,yFit,'b-' , 'LineWidth',1);

grid on;

Answer 1

Hello Ash,

Effectivenormalstress=[41,79,119,159,197,80]';  % make these into column vectors
Maximumshearstress=[34,73,97,138,173,56]';
x=Effectivenormalstress;
y=Maximumshearstress;
c = x\y              
xplot = 1:200;
plot(xplot,c*xplot,x,y,'o');grid on

The idea is to fit the linear relation x*c = y in the least squares sense where x and y are column vectors.