If I have three graphs and I want to place them over one another so that their mean values align, and then want to create a trend line among those graphs how would I do this?

%example
x=[1:0.03:500];
y=x^4;
i=[100:0.01:600];
y2=x^2+30;

plot(x,y,i,y2);

[Adam Danz]

Your example doesn't work.

What do you mean by aligning their mean values? Do you mean for each line you'd like to subtract the mean?

x = x-mean(x); 
y = y-mean(y);

Answer 1

[Image Analyst]

Try this:

x1=[1:0.03:500];
y1 = x1.^4;
x2 = [100:0.01:600];
y2 = x2.^2+30;

plot(x1,y1, 'r-', 'LineWidth', 2);
hold on;
plot(x2,y2, 'b-', 'LineWidth', 2);
grid on;

xAll = [x1, x2];
yAll = [y1, y2];
[coefficients, S, mu] = polyfit(xAll, yAll, 1)
numPoints = max([length(x1), length(x2)])
fittedX = linspace(min(xAll), max(xAll), numPoints);
fittedY = polyval(coefficients, fittedX, S, mu);
plot(fittedX, fittedY, 'g-', 'LineWidth', 2);
legend('y1', 'y2', 'linear fit y', 'location', 'north');

Is that what you're thinking of? Note that because you have more of the flatter curve points, it's pulling down the "average" line curve. If you don't want that you can use interp1 to resample to have them both have the same number of points and same starting and ending x values.

[Keon Walters]

That’s perfect thanks!!