R: [math] Compute derivatives for bidimensional interpolated function

[Alessandro Moscatelli]

It seems that the SplineInterpolator per row/columns is exactly what the 
depracted Cubic Interpolator was doing.
So, nevermind, I got my answer. It made sense indeed.

Looking further into the code for PR porpuses.

Thank you
Alessandro

Da: Alessandro Moscatelli<mailto:alessandro.moscate...@live.com>
Inviato: mercoledì 20 luglio 2022 15:01
A: Commons Users List<mailto:user@commons.apache.org>
Oggetto: R: [math] Compute derivatives for bidimensional interpolated function

We are talking about making a PR, am I right ?
So, I guess, there is no way to do this at the moment.

Isn’t there any way to combine multiple UnivariateDifferentiableFunction and/or 
DerivativeStructure computed on different free parameters (es x and y) ?
I dunno if I am exaplining this correctly :

I am talking about using a SplineInterpolator to compute multiple 
SplineInterpolatorFunction, one for each row and column of the grid …
Can this make sense ?

Anyway I’ll take a look at the source code and try to understand what’s needed 
to make BicubicInterpolatingFunction an implementation for that new interface 
BivariateDifferentiableFunction.

Thank you
Alessandro

Da: Gilles Sadowski<mailto:gillese...@gmail.com>
Inviato: mercoledì 20 luglio 2022 14:10
A: Commons Users List<mailto:user@commons.apache.org>
Oggetto: Re: [math] Compute derivatives for bidimensional interpolated function

Hello.

Le mer. 20 juil. 2022 à 12:29, Alessandro Moscatelli
 a écrit :
>
> Hi everybody !
>
> I have an xyz grid of points.
> I want to interpolate and compute derivations along x, along y, and along xy.
>
> If I understood correctly, I can’t use PiecewiseBicubicSplineInterpolator 
> (this was my first attempt), since it interpolates into 
> PiecewiseBicubicSplineInterpolatingFunction which doesn’t implements 
> MultivariateDifferentiableFunction .
>
> I need a function able to return DerivativeStructure, am I right ?

I think so.

>
> Then I double checked and found a deprecated BicubicSplineInterpolator.
> That interpolator lets me directly compute derivatives I need.

This class does not exist in the development version that will become
the next major version (4.0).

> Am I missing something ?
> How can I do what I need without using deprecated BicubicSplineInterpolator.

As you suggest, it would be great that you explore how to provide
access to the derivatives (which the interpolating functions are able
to compute, since they are polynomials).

A minimal change would perhaps be that "BicubicInterpolatingFunction"
implements a new "BivariateDifferentiableFunction" interface:
---CUT---
public interface BivariateDifferentiableFunction extends
BinaryOperator
{}
---CUT---

Regards,
Gilles

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R: [math] Compute derivatives for bidimensional interpolated function

[Alessandro Moscatelli]

We are talking about making a PR, am I right ?
So, I guess, there is no way to do this at the moment.

Isn’t there any way to combine multiple UnivariateDifferentiableFunction and/or 
DerivativeStructure computed on different free parameters (es x and y) ?
I dunno if I am exaplining this correctly :

I am talking about using a SplineInterpolator to compute multiple 
SplineInterpolatorFunction, one for each row and column of the grid …
Can this make sense ?

Anyway I’ll take a look at the source code and try to understand what’s needed 
to make BicubicInterpolatingFunction an implementation for that new interface 
BivariateDifferentiableFunction.

Thank you
Alessandro

Da: Gilles Sadowski
Inviato: mercoledì 20 luglio 2022 14:10
A: Commons Users List
Oggetto: Re: [math] Compute derivatives for bidimensional interpolated function

Hello.

Le mer. 20 juil. 2022 à 12:29, Alessandro Moscatelli
 a écrit :
>
> Hi everybody !
>
> I have an xyz grid of points.
> I want to interpolate and compute derivations along x, along y, and along xy.
>
> If I understood correctly, I can’t use PiecewiseBicubicSplineInterpolator 
> (this was my first attempt), since it interpolates into 
> PiecewiseBicubicSplineInterpolatingFunction which doesn’t implements 
> MultivariateDifferentiableFunction .
>
> I need a function able to return DerivativeStructure, am I right ?

I think so.

>
> Then I double checked and found a deprecated BicubicSplineInterpolator.
> That interpolator lets me directly compute derivatives I need.

This class does not exist in the development version that will become
the next major version (4.0).

> Am I missing something ?
> How can I do what I need without using deprecated BicubicSplineInterpolator.

As you suggest, it would be great that you explore how to provide
access to the derivatives (which the interpolating functions are able
to compute, since they are polynomials).

A minimal change would perhaps be that "BicubicInterpolatingFunction"
implements a new "BivariateDifferentiableFunction" interface:
---CUT---
public interface BivariateDifferentiableFunction extends
BinaryOperator
{}
---CUT---

Regards,
Gilles

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To unsubscribe, e-mail: user-unsubscr...@commons.apache.org
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