Thread Subject: simple problem (?)

hello,
i have a problem for which i'm sure a solution exists already ..
i have an independent variable 'x' and its corresponding dependent
'y' ... is there anyway using matlab where i can get the corresponding
y-variable for whatever value of x i choose, and vice-versa.
thanks.

rush <rush3k@gmail.com> wrote in message <de304b45-bc9a-49ff-adce-
9e96a2bd7d14@n20g2000hsh.googlegroups.com>...
> hello,
> i have a problem for which i'm sure a solution exists already ..
> i have an independent variable 'x' and its corresponding dependent
> 'y' ... is there anyway using matlab where i can get the corresponding
> y-variable for whatever value of x i choose, and vice-versa.
> thanks.

This is a well studied problem, but one with many
answers. The general problem is called interpolation.
The issue is that you need to choose a method that
is appropriate to your specific problem.

Several reasonable methods will be found in the
function interp1, assuming that you have only one
independent variable.

HTH,
John

rush <rush3k@gmail.com> wrote in message <de304b45-bc9a-
49ff-adce-9e96a2bd7d14@n20g2000hsh.googlegroups.com>...
> hello,
> i have a problem for which i'm sure a solution exists
already ..
> i have an independent variable 'x' and its corresponding
dependent
> 'y' ... is there anyway using matlab where i can get the
corresponding
> y-variable for whatever value of x i choose, and vice-
versa.
> thanks.

Are the variables x and y given as lists of numbers, or do
you have y as a function of x?

If it's the former, then the solution to your problem is
could be as simple as running a search on the lists.

If it's the latter, then there are issues that go beyond
just computing x given a y. Do you have a specific
function and can you post it? Or are you interested in
this problem for arbitrary functions?

Charles.

On Jan 3, 9:54 am, "Charles Cuell" <cu...@math.usask.ca> wrote:
> rush <rus...@gmail.com> wrote in message <de304b45-bc9a-
>
> 49ff-adce-9e96a2bd7...@n20g2000hsh.googlegroups.com>...
>
> > hello,
> > i have a problem for which i'm sure a solution exists
> already ..
> > i have an independent variable 'x' and its corresponding
> dependent
> > 'y' ... is there anyway using matlab where i can get the
> corresponding
> > y-variable for whatever value of x i choose, and vice-
> versa.
> > thanks.
>
> Are the variables x and y given as lists of numbers, or do
> you have y as a function of x?
>
> If it's the former, then the solution to your problem is
> could be as simple as running a search on the lists.
>
> If it's the latter, then there are issues that go beyond
> just computing x given a y. Do you have a specific
> function and can you post it? Or are you interested in
> this problem for arbitrary functions?
>
> Charles.

Thanks for the information John and Charles. The problem was solved
using the interp1 as adviced by John. I dont have a function
representing y, that would made the problem easier. . It will be
interesting to know how to "search on the lists" as Charles has
suggested. Thank you.