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Topic: interpolate
Replies: 14   Last Post: Apr 9, 2015 1:34 PM

 Messages: [ Previous | Next ]
 maryam Posts: 17 Registered: 12/25/12
Re: interpolate
Posted: Dec 28, 2012 4:35 PM

"maryam" wrote in message <kbkj8i\$i6n\$1@newscl01ah.mathworks.com>...
> dpb <none@non.net> wrote in message <kbhqvf\$l2s\$1@speranza.aioe.org>...
> > On 12/26/2012 7:45 PM, maryam wrote:
> > > dpb <none@non.net> wrote in message <kbg5ol\$ugl\$1@speranza.aioe.org>...
> > >> On 12/26/2012 5:03 PM, maryam wrote:
> > >> > dpb <none@non.net> wrote in message <kbfhar\$1lo\$1@speranza.aioe.org>...
> > ...
> >

> > >> >> doc interp1
> > >> >>

> > >> >> >> X = 0:10; V = sin(X); Xq = 0:.25:10;
> > >> >> >> Vq = interp1(X,V,Xq);

> > ...
> >

> > >> > thank you very much for your answer but I mean we have a matrix n-by-m:
> > >> > assume M= [a b c;d e f; g h i]
> > >> > I want to interpolate its rows so that is equal to
> > >> > M=[a a+d a+2d a+3d ... 7d b b+d ... b+7d c... c+7d ; d... d+7d...

> > >> f+7d ;
> > >> > g ... i+7d]
> > >> > Can you explain me how I could do it?

> > >>
> > >> I'm virtually certain you asked this same question some days ago and I
> > >> told you then the same thing...
> > >>
> > >> Use interp1() as the above example w/ an interpolating vector of the
> > >> points at which you want interpolants. Here's why I think I remember
> > >> the question and the response, as I pointed out then, since interp1()
> > >> works on columns you'll need to transpose, interpolate, then transpose
> > >> back.
> > >>
> > >> I can't interpret the above [a a+d a+2d ... ) precisely but assuming d
> > >> here is a different 'd' than that of the value in the original M(2,1)
> > >> and is just a delta then the interpolant would seem to be
> > >> linspace(0,N*d,N+1) where N is the number of intervals (7 above) added
> > >> to a, b, c, ..., etc.
> > >>

> > ...
> >

> > > thank you so much, I'm Beginner in matlab,
> > > I apologize for my request
> > > Is it possible give me matlab code of my question?
> > > I couldn't use 'for' command or M(:,columns) ...
> > > my matrix is 1000-by-1200 d=delta=1/16
> > > its values (arrays) is arbitrary here

> >
> > That's identical to the example I gave except on an array instead of a
> > vector...and a still-to-be-determined precisely interpolant.
> >
> > What does the 1/16 delta refer to--is it a constant or a fraction of the
> > distance between columns, or what? Your description isn't precise (or
> > at least I can't decipher what it is you want clearly enough to actually
> > write a piece of specific code).
> >
> > Can you give a very small example of a dataset that you could compute
> > the desired result of by hand? It wouldn't have to be but one row and a
> > few values to illustrate what you're actually trying to do...
> >

> -------------------------------------------------------
> Here is a simple code, that Matlab wouldn?t run it:
>
> ti=1.44e-4; to=1.48e-04; dt=1e-9;
> m=2*ceil(.5*(to-ti)/dt);
> n=linspace(0,2,600);
> t=ti+(0:m-1)*dt;
> s=zeros(600,m);
> for k=1:600
> s(k,:)=exp(i*2*pi*10e5*sqrt(3*n(k))+i*pi*t.^2);
> end
> s1=s;
> d=(10-n).^2/8;
> for k=1:600;
> for r=1:m-round(max(d));
> s1(k,m)=s(k,m+d(k));
> end
> end
>
> each d vector element like d(1)=12.5 includes an integer part(12) and a fractional one(0.5).
> I need an interpolator to move the data an arbitrary fraction of the space between each 2 elements, this fraction is quantized to 1/16 of the space between 2 elements, so 15 different interpolators are needed to move the data by i /16 of this space, where i = 1 : 15, A simple interpolator is obtained from a truncated sinc function that the coefficients are weighted by a window like kaiser.
>
> I didn?t know how to round d vector?
> And how could I interpolate rows of s matrix?
>
> I would really appreciate your kind help

------------------
One thing I forgot, after interpolation we shift its value to nearest element

Date Subject Author
12/26/12 maryam
12/26/12 dpb
12/26/12 maryam
12/26/12 dpb
12/26/12 maryam
12/27/12 dpb
12/28/12 maryam
12/28/12 maryam
12/28/12 maryam
12/28/12 dpb
12/30/12 Steven Lord
12/31/12 dpb
4/9/15 rakeshElango
4/9/15 Steven Lord