rem Linear Regression

cls
print "Linear Regression"
print

rem variables

j=0
k=0
l=0
m=0
r2=0

rem data entry
input "number of known points? ";n
for t=1 to n
 print
 print "x(";t;")= ";
 input " ";x
 print "y(";t;")= ";
 input " ";y
 if n=2 and t=1 then
    x1=x
    y1=y
 end if
 j=j+x
 k=k+y
 l=l+x^2
 m=m+y^2
 r2=r2+x*y
next t

rem compute curve coefficient
if n=2 then
 b=(y1-y)/(x1-x)
 a=y-b*x
else
 b=(n*r2-k*j)/(n*l-j^2)
 a=(k-b*j)/n
end if

print
print "f(x)=";a;"+(";b;"*x)"
print

rem compute regression
j=b*(r2-j*k/n)
m=m-k^2/n
k=m-j
r2=j/m
if n>2 then
 print "Coefficient of Determination (r^2)= ";r2
 print "Coefficient of correlation (r^.5)= ";(r2^.5)
 print "Standard error of estimate (k/(n-2)^.5= ";(k/(n-2))^.5
end if

rem "estimate y coordinate"
[again]
print
print "Interpolation (enter x=q to end program) ";
input "x= ";x$
if x$="q" then
 end
end if
x=val(x$)
print "y= ";a+b*x
goto [again]