[Math] Bicubic interpolation

[Gilles Sadowski <gi...@harfang.homelinux.org>]

Hello.

This is in reference to the second feature request in issue
  https://issues.apache.org/jira/browse/MATH-353

If I'm not mistaken, this interpolation algorithm requires a regular grid of
samples.
The method "interpolate" in interface "MultivariateRealInterpolator" cannot
enforce this as the sample coordinates must be specified independently for
each sample; they are passed in a single variable:
  void interpolate(double[][] samples, double[] values)
e.g. in 2D, samples[i][0] is the x-coordinate,
            samples[i][1] is the y-coordinate,
            values[i] is f(samples[i][0], samples[i][1])

For a grid in 2D, there should be:
  void interpolate(double[] x, double[] y, double[][] values)
i.e. x[i] is the i-th grid x-coordinate
     y[j] is the j-th grid y-coordinate
     both x and y must be sorted in increasing order
     values[i][j] is f(x[i], y[j])

Should we create a "BivariateRealGridInterpolator" interface?

Best,
Gilles

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Re: [Math] Bicubic interpolation

[Luc Maisonobe <Lu...@free.fr>]

Gilles Sadowski a écrit :
> Hello.
> 
> This is in reference to the second feature request in issue
>   https://issues.apache.org/jira/browse/MATH-353
> 
> If I'm not mistaken, this interpolation algorithm requires a regular grid of
> samples.
> The method "interpolate" in interface "MultivariateRealInterpolator" cannot
> enforce this as the sample coordinates must be specified independently for
> each sample; they are passed in a single variable:
>   void interpolate(double[][] samples, double[] values)
> e.g. in 2D, samples[i][0] is the x-coordinate,
>             samples[i][1] is the y-coordinate,
>             values[i] is f(samples[i][0], samples[i][1])
> 
> For a grid in 2D, there should be:
>   void interpolate(double[] x, double[] y, double[][] values)
> i.e. x[i] is the i-th grid x-coordinate
>      y[j] is the j-th grid y-coordinate
>      both x and y must be sorted in increasing order
>      values[i][j] is f(x[i], y[j])
> 
> Should we create a "BivariateRealGridInterpolator" interface?

This is a good idea.

Luc

> 
> Best,
> Gilles
> 
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> To unsubscribe, e-mail: dev-unsubscribe@commons.apache.org
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> 
> 


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