can anyone help please as i m trying to force a zero intercept for this figure using polyfit

x2 = [383.3 306.83 258.66 210.49 152.89 104.72 48.17];
y2 = [1.09 0.89 0.78 0.61 0.45 0.3 0.17];
plot(x2,y2,'ro');hold on; grid on; xlim([0 420]); ylim([0 2]);
xlabel('Rotor speed,\omega_{R} (rad/s) ');
ylabel('Inverse precession speed,1/\omega_{P} (s/rad)');
title('Curve of angular speed against inverse precession on angular speed');
p = polyfit(x2,y2,1);
pp = polyval(p,x2);
hold on
plot(x2,pp,'-r');

Answer 1

[Star Strider]

The polyfit function will not let you force a zero intercept, but the mldivide operator (\) will:

x2 = [383.3 306.83 258.66 210.49 152.89 104.72 48.17];
y2 = [1.09 0.89 0.78 0.61 0.45 0.3 0.17];

p = x2(:)\y2(:);                                % Calculate Slope, Forcing Zero Intercept
p =
     2.9039e-003

In the context of your code:

x2 = [383.3 306.83 258.66 210.49 152.89 104.72 48.17];
y2 = [1.09 0.89 0.78 0.61 0.45 0.3 0.17];
plot(x2,y2,'ro');hold on; grid on; xlim([0 420]); ylim([0 2]);
xlabel('Rotor speed,\omega_{R} (rad/s) ');
ylabel('Inverse precession speed,1/\omega_{P} (s/rad)');
title('Curve of angular speed against inverse precession on angular speed');
p = x2(:)\y2(:);                                % Calculate Slope, Forcing Zero Intercept
pp = p*x2;
hold on
plot(x2,pp,'-r');

[francis thierry fonkui happi]

thanks!!!!!

[Star Strider]

My pleasure!

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