Code seems to not be printing out the value I need, as well as not graphing points on the figure. Need help, I don't know how to fix this.

clear


clc

 m1=1000;

 m2=500;

 m3=200;

 rp=87;

 r2=[58.7 27.8 20 59 30 31.2 68.5 67 34 60 39 50.3 50 45.3 45]';

 r3=[12.89 20.65 226 120 217 193.1 91.6 110 197.5 166 158.3 142.1 150 176.5 122]';




G = ones(length(m1), 2);

G(:,2) =  m1;


m = G \ m2



m_b=(m2/rp)*((-m1)/(rp));



sigma = sqrt(sum((m2-G*m).^2)./(length(m1)-2));


se1 = sigma.*sqrt(1./((length(m1)+mean(m1)^2/((length(m1)-1)*std(m1)^2))));

se2 = sigma.*sqrt(1./((length (m1)-1)*std(m1)^2));


Ci1=tinv(.975,length(m1)-2).*se1;

Ci2=tinv(.975,length(m1)-2).*se2;

% creating a line of best fit

X = [min(m1);1e-3;max(m1)]';

Y = m(1,1) + m(2,1).*X;


SE=sigma.*sqrt(1/length(m1)+(X-mean(m1)).^2./((length(m1)-1)*std(m1).^2));

Ci=tinv(.975,length(m1)-2).*SE;


figure(1)


clf


plot(m1, m2, 'ob')


hold on


% plotting the conidence intervals

plot (X, Y, 'R')

plot(X,Y+Ci,'g--')

plot(X,Y-Ci,'g--')


hold off



xlabel('$$-$$','interpreter','latex')


ylabel('$$-)$$','interpreter','latex')


print(figure(1), '-dpng', 'figure1')

[Star Strider]

I cannot read the image. As is, it is too small, and when I enlarge it, it iss not distinct enough to read.

I am guessing that you are dong some sort of regression, and then want to plot the data, regression, and oconfidence intervals.

Please describe what you want to do.

[ktar]

There is a model equation (included in code) that is supposed to give me the slope of the line/ value for m. Also I want my figure to have dots (data points form my data).

Answer 1

[Star Strider]

Now I can read it, although understranding your notes remains a problem.

You still have not described what you want to do with ‘r2’ and ‘r3’.

If you want to calculate the copnfidence intervals on the linear regression and the parameters, use the Statistics and Machine Learning Toolbox regress (link) function. Calculating the confidence intervals on a regression involves calculating the covariance matrix of your data. It is easier to let regress do it.

[ktar]

Its from a physics lab I did. r2 and r3 are data points taken from the lab. The model equation which is what is already put in my code. What I'm trying to get from the lab is the value for m. I don't know how else to clarify this futher. I am not a matlab expert either so that is why I posted my question. (Also variable b is the slope in my work).

[Star Strider]

‘The model equation which is what is already put in my code.’

Where?

What is your model?

I can’t figure it out from your code or your class notes!

What is or are your independent variable(s), what is or are your dependent variable(s), and how are they related in your model?

[ktar]

m_b=(m2/rp)*((-m1)/(rp));

[Star Strider]

Please note that:

m_b=(m2/rp)*((-m1)/(rp));

does not answer my question, since these are scalar quantities, anbd appear to be unrelated to ‘r2’ and ‘r3’ that appear to be data.

Please be specific. Tell me what your data are, and what you want to do with them.

Answer 2

[Image Analyst]

"seems to not be printing out the value" <==== Use fprintf() or disp() or leave off semicolons to print to the command window. Don't use print() like you had.

[ktar]

can you add it to my code that I posted, I'm not an expert and dont wanna make a mistake. Also thank you for your help! Also will this print out data points (blue dots) on my figure and give me the value for m?