Finding difference between two curves

I am very very new to matlab. I need to find the average of two curves and then subtract it from the third. The problem is that although they have the same limits they do not have the same x-values.

[Emma]

I can't take the means of the points as they have different x-values and therefore are not the same thing. I am looking at temperature vs. signal. Although the data sets are all from 50-900degC they are not at the exact same temperature.

[Emma]

http://s1337.beta.photobucket.com/user/Lovelle91/media/Fig1_zps51626496.png.html

Answer 1

[Azzi Abdelmalek]

y1=rand(1,10);
y2=rand(1,12);
y3=rand(1,15);
out=y3-mean([y1 y2])

[Azzi Abdelmalek]

Do you want to interpolate?

[Emma]

I was thinking interpolation between each point or using "fit" as my curves I do not think that my curves will fit to a polynomial (see picture)

[Azzi Abdelmalek]

T1=50:20:900
T2=50:25:900
T3=50:30:900
y1=rand(1,numel(T1))
y2=rand(1,numel(T2))
y3=rand(1,numel(T3))

T=unique([T1 T2 T3])
Y1i=interp1(T1,y1,T);
Y2i=interp1(T2,y2,T);
Y3i=interp1(T3,y3,T);

out=Y3i-mean([Y1i;Y2i])