How to use symsum to calcolate residuals

Hello everyone!

Could someone help me, please?

I have these vectors:

x = [0; 0; 0; 0; 1]           
y = [1; 0.15; 0.03; 0; 0.89]             
z=[0; 0.35; 0.70; 1; 0.86]

I would like to calculate this redisuals' expression:

Rtot = sumRi , Ri = (zi - a*xi - b*yi - c*xi*yi - d).^2

for each index i. For example for i = 4 I would have:

Ri = (0.86 - a*1 - b*0.89 - c*1*0.89 - d).^2.

Is there a way to perform this sum?

Thank you very much in advance for your suggestions and help.

Regards

Laura

[darova]

Just type

Ri = (zi - a*xi - b*yi - c*xi*yi - d).^2;
sum(Ri)

simple

[laura bagnale]

Dear Darova,

thank you for your reply. The problem is that I do not know how to insert the different xi and yi sequentially into the same formula of Ri for having a summation of Ri.

Thank you

[Walter Roberson]

R = (z - a*x - b*y - c*x.*y - d).^2;
Rtot = sum(R);

[laura bagnale]

Thank you very much to both of you for your help.

I tried and it works!

Regards

Laura

[laura bagnale]

How Can I accept your cooment/answer?

Thanks a lot

Answer 1

[Walter Roberson]

Bringing down from above,

R = (z - a*x - b*y - c*x.*y - d).^2;
Rtot = sum(R);