Linear least-squares fit

Hello, I'm trying to find the least squares fit between two sets of data but all the examples I've seen are for one set. Would anyone mind helping me? Please and thank you!

Code:

%%Part 2
% Graph: Transducer & Scannivalve vs Manometer

x1 = [.054 .107 .177 .272 .383 .514 .809];  %transducer (V)
x2 = [.162 .306 .495 .749 1.051 1.402 2.193];  %scannivalve (V) - switched to +
y = [.182 .47 .841 1.349 1.945 2.615 4.241];   %manometer (in. of H20)

figure(1)
plot(x1,y,'x',x2,y,'o');
title('Part 2'); xlabel('Voltage, V'); 
ylabel('Pressure, P'); grid on
legend('Tansducer','Scannivalve');

Answer 1

[Star Strider]

See if this does what you want:

dsnmtx = [ones(size(y',1),1) x1' x2'];          % Design Matrix
B = dsnmtx\y';                                  % Estimate Parameters
yfit = [ones(size(y',1),1) x1' x2']*B;          % Estimated ‘y’

figure(1)
stem3(x1', x2', y')
hold on
plot3(x1', x2', yfit)
hold off
grid on