Hi Steve,
With regards to curve fitting, when you choose the points, then you can fit it to any function using lsqcurvefit, since you know x and y.
Here is an example similar to the one you describe above. I select the values you described, and show the result in a plot:
x = [1 2 3 4 5 6 7 8];
y = [3 4 5 6 7 8 9 10];
range = [2,3,4,7];
xdata = x(range);
ydata = y(range);
fun = @(c, xdata) c(1)*xdata + c(2);
x0 = [1.2,1.8]
coeffs = lsqcurvefit(fun, x0, xdata, ydata);
figure(); hold on;
plot(xdata, ydata, 'o');
plot(xdata, fun(coeffs, xdata))
I hope that helps, and is similar to what you are looking for,
Michael
