Help aligning two vectors with one centred on zero.

Question

Jason 2016-10-25

评论： Chaya N 2016-10-25

I have a set of x values:

x1=-31, -15.5, 0, 14.9,30.2

I know that the separation should be 15 (=pitch) so I want to plot x1 against xreal then do a fit and look at the largest deviation.

I can create:

xreal=Pitch*((1:numel(x1)));

But I can't figure out how to align them AROUND 0,e.g

xreal = -30, -15, 0 , 15, 30

then I can easily plot x1 against xreal and linearly fit.

Answer 1

LauraLee Austin 2016-10-25

How about this, it should allow the location of 0 in x1 to change and the number of values in set x1 to be variable as well. if true

x1 = [-31, -15.5, 0, 14.9,30.2];
Pitch = 15;
idx = find(x1==0);
numel(x1)
xreal=(Pitch*(1-idx)):Pitch:(Pitch*(numel(x1)-idx));

Jason 2016-10-25

Perfect, thankyou

Answer 2

Chaya N 2016-10-25

编辑：Chaya N 2016-10-25

xreal=Pitch*((1:numel(x1)) - ceil(numel(x1)/2))

Jason 2016-10-25

doesn't this assume that the x1 values are symmetrical around 0. although shown in the example, this may not always be the case.

Chaya N 2016-10-25

"...align them AROUND 0"

Exactly as asked!

Answer 3

Matt J 2016-10-25

xreal=xreal-mean(xreal);

Matt J 2016-10-25

编辑：Matt J 2016-10-25

The mean of xreal would still be at zero. That is the only interpretation of the requirement "centered AROUND 0" that we can intuit from your post.

Jason 2016-10-25

Yes sorry, I only thought of it after you had answered.