MATLAB Central Newsreader - interp3

interp3

Ross — Wed, 08 Apr 2009 02:55:13 -0400

Hi everyone,

I am not sure if matlab has a built-in function for this.

Instead of using interp3 to linearly interpolate a three-dimensional
function V as follows,

VI = interp3(X,Y,Z,V,X,Y,ZI),

I would like to retrieve the value of ZI given that VI,X,Y are known.

Thanks!!
R

Re: interp3

Ross — Wed, 08 Apr 2009 03:00:23 -0400

PS:
Z and V are also known.

Re: interp3

John D'Errico — Wed, 08 Apr 2009 03:30:04 -0400

Ross <fed.rossi@gmail.com> wrote in message <48891dbe-8e0b-410e-9cf4-4dda5e08f94f@v28g2000vbb.googlegroups.com>...
> Hi everyone,
>
> I am not sure if matlab has a built-in function for this.
>
> Instead of using interp3 to linearly interpolate a three-dimensional
> function V as follows,
>
> VI = interp3(X,Y,Z,V,X,Y,ZI),
>
> I would like to retrieve the value of ZI given that VI,X,Y are known.

When you fix the value of X and Y, this reduces
the problem to a 1-d inverse problem. I would
convert it to a simple problem V(Z) - V0 = 0, for
the given value of V. Now it is just a question of
finding the zero crossings. If you do not know
how to do that, then look for "intersections" on
the file exchange (by Doug Schwarz.)

John

Re: interp3

Ross — Wed, 08 Apr 2009 04:38:16 -0400

Thanks John!
R

On Apr 7, 11:30=A0pm, "John D'Errico" <woodch...@rochester.rr.com>
wrote:
> Ross <fed.ro...@gmail.com> wrote in message <48891dbe-8e0b-410e-9cf4-4dda=
5e08f...@v28g2000vbb.googlegroups.com>...
> > Hi everyone,
>
> > I am not sure if matlab has a built-in function for this.
>
> > Instead of using interp3 to linearly interpolate a three-dimensional
> > function V as follows,
>
> > VI =3D interp3(X,Y,Z,V,X,Y,ZI),
>
> > I would like to retrieve the value of ZI given that VI,X,Y are known.
>
> When you fix the value of X and Y, this reduces
> the problem to a 1-d inverse problem. I would
> convert it to a simple problem V(Z) - V0 =3D 0, for
> the given value of V. Now it is just a question of
> finding the zero crossings. If you do not know
> how to do that, then look for "intersections" on
> the file exchange (by Doug Schwarz.)
>
> John